Khả năng ứng dụng các dây nano ZnO được chế tạo bằng phương pháp bốc bay nhiệt

DAI HOC QUOC GIA HA NOI
TRUONG OAI HOC KHOA HOC TU NHIEN
• • • •
* * *
V\
bl
TA\l!
KHA NANG
LTNG
DUNG CAC DAY NANO ZnO
Dl/OC
CHE TAO BANG
PHl/ONG
PHAP BOG BAY NHIET
MA
SO: QT - 06 - 09
CHU TRI DE
TAI: PCS. TS. Ta Dinh Canh
I
CAN
BO
THAM
GIA: CN. Tran Thi
Quynh
Hoa
CN.
Nguyen
Viet Tuyen
HA
Ndi
- 2006

^^Al
HOC
QOOC
GIA HA
NQI
i^UN<J-
TAIV THONG
TIN THU VIEN
DT/63^
hkO
cAo
TOM TAT
De tai:
KHA NANG
QNG
DUNG
GAG DAY
NANO
ZnO
DUOC
GHE
TAO
BANG PHUONG PHAP
BOG BAY
NHIET
Ma so: QT - 06 - 09
Chii
tri 66 thi:
PGS.
TS. Ta

Diiili
Canh
Can bo tham gia: CN. Tran Thi Quynh Hoa
CN. Nguyen Viet Tuyen
1.
Muc tieu de tai:
Hien nay vat lieu cau
true
nano mot chieu (day nano, thanh nano,
bang nano) dang
du-ffc
quan tam dac biet vi tiem nang ung dung cua no
trong
ITnh virc
linh kien dien tir va quang dien
tir
co kich
thu-ffc
nano.
Vat lieu cau
true
nano mot chieu co the dune
nhu*
cac cau
true
thanh
•
•
•
C3

phan de che tao cac linh kien dien tu va quang dien tir kfch
thu'dc
nano.
Cac vat lieu nay co the
duae
tong hop bang nhieu
phu-ang
phap khac
nhau
nhu*:
phuo'ng
phap van chuyen
tii'
pha hoi
[1-3],
phu'O'ng
phap lang
dong hoa hoc tir pha hoi
[4],
phuong phap ket tua bang dien [5], sol-gel
16]
Trong so cac oxit ban dan, ZnO la chat ban dan
viing
cam thang, co
do rong vung cam
o*
nhiet do phong
£g~
3,37 eV va nang
ino-ng

lien ket
exciton
co*
60 meV. Cac day nano, thanh nano ZnO la cac vat lieu co
nhieu trien
vpng
trong viec che tao cac lade, diot phat quang vung
tii*
ngoai
(sii-
dung hieu
ling
exciton nhiet do phong), cac transit© hieu ung
tru-crng,
chuyen mach quang va cac
senso'
khi
Trong bai bao cao nay, chiing toi tr
inh
b ay cac ket qua che tao day
nano,
thanh nano ZnO bang phuong phap van chuyen tir pha
hai
kh
ong
V
a
CO
chat xiic tac Au trong moi truong
khi

mang la Ar.
2,
Noi dung nghien
cihi:
De thirc hien
dugc
muc tieu neu
a
tren, de tai da giai quyet
duae
cac
van
de sau:
+
xay
dung he tao day nano ZnO
- Lo ong ((j)
=40mm)
tao nhiet do tren
duori
1000^
co do on dinh
cao (16
CO
sai so nho ca
±r
va chay theo
chuomg
trinh)
-

Khi
mang Ar co do sach 99%
+
Tdng hop
ca'u true
nano ZnO
1-chieu
tCr
pha
hai-ran
(VS)
+ Tong hop cau
true
nano ZnO
1-chieu
tir
pha
hai-long-ran
(VLS)
bang
each sir
dung mang vang
(chai
xuc tac) nhu
m6t
dung moi tai nhiet
do
cao.
+ Khao sat
tinh

chat cau
true
cua day nano ZnO
4-
Khao sat tfnh chat huynh quang va
khich
thich huynh quang ciia day
nan6 ZnO
+Xfly
dung
thiinli
cong he
tlurc
nghiem do
sir
phu thuoc dien tro'
ciia
mau vao do am
ciia
moi truong
3.
Cac ket qua dat
dirac:
+
Che tao thanh cong day nano ZnO eo
ducmg kinh
nho
tir
30-60nm
tren de Si bang 2

phirang
phap VS va VLS co dung m6i
trircmg
thoi
khi
tra Ar.
+
khao sat
tinh chA'l
cau true
ciia ca'u triic
nan6 ZnO phu thuoc vao
nhiet
d6
de,
th5i
gian tao
mSu,
do day ciia cha't
xiic
tac vang.
-I-
Khoa sat
tinh
chat huynh quang va kfch thich huynh quang
ciia
cac
day nan6 ZnO da che tao.
H-Birdc
dau phat hien hieu ung nhay am ciia ZnO,

ma
ra kha nang
irng dung ZnO nano lam vat lieu sensor trong
tirang
lai.
+
Cong tac nghien
cii'u:
da cong bo 3 bai bao
1/
Tran Thi Quynh Hoa, Ta Dinh Canh, Nguyen Ngoc Long, Nguyen Viet
Tuyen,
"Zinc
oxide nanostructure for humidity sensor", VNU
Journal of Science, Mathematics - Physics, 2006 (in press).
2/
Ta Dinh Canh, Nguyen Ngoe Long, Nguyen Viet Tuyen, Tran Thi
Quynh Hoa, Cao Van Tuan, "Multiform ZnO nanostructures
fabricated by vapor-phase transport method without catalyst",
VNU Journal of Science, Mathematics - Physics, 2006 (in press).
3/
Tran Thi Quynh Hoa, Ta Dinh C anh, Nguyen Ngoc Long, Nguyen
Viet Tuyen and Nguyen Duy Phuong,
"Photoluminescence
of ZnO
nanostructure prepared by catalyst- assisted vapor-liquid-solid
technique", Tuyen lap bao cao
IIQI
nghj khoa
hpc

quang
ph6
toan
(liioe hin (hiV
IV,
('iiii
llu),
S/2()()(),
(il;l iilifm
in).
+ Cong tac dao tao :
* Da
hiromg
dan 2 khoa luan tot nghiep
-Vu Tien
L6c"che
tao mot sd cau triic nano ZnO bang phuang phap
b6'c
bay
nhiet" (2006)
-NguySn
Viet Tuyen "Che tao va khao sat dTa nano dang
I6i/v6 ciia
Zn/ZnO
bang phuang phap boc bay nhiet" (2006)
* Da hu6ng
dSn
2 luan van cao hoc:
-TrSn
Thi Quynh Hoa,

"
Che tao va khao sat mot sd tinh cha't
ciia
day nano
ZnO
duae
che tao bang phuang phap bdc bay nhiet" (2006)
- Cao Van
Tuah,
"Che tao va khao
sdt
ca'u triic
nan6
ZnO pha tap Co bang
phuang
phcip
bdc bay nhiel'\ (2006)
4.
Tinh hinh
su dung kinh
phi:
Tong kinh
phi
thuc chi: 15.000.000 dong
(mu5i
lam trieu dong chan).
Trong do cac khoan da chi:
Thanh toan dich vu cong
c6ng
: 600.000 d (tien dien)

Thue mu6n : 6.000.000 d
Chi
phi
vat tu hoa chat: 7.800.000 d
Chi
phi
khac (QLCS): 600.000 d
Da th6ng qua
chijng
ttj*
tai phong tai vu.
Xac nhan
ciia
ban chu nhiem Khoa
(Ky va ghi ro ho ten)
?5
Chia tri
de tai
(Ky va ghi ro ho ten)
PGS.TS.NguyIn
The
Binh
PGS.TS.Ta
Dinh
Canh
Xiic nhAn ci'ui 'IVircnig
DI
IKI II'N
OHO HiEu
IRU6N&

jblu/n/
c/IioLfiit
Brief of the Report
L The title of the project.
The possible applications of ZnO nanowires, prepared by vapor
phase transport
method.
The code number: QT - 06 - 09.
2.
Main responsible person: Assoc.
Prof.
Dr. Ta Dinh Canh.
3.
Main implementation numbers
Bachelor: Tran Thi Quynh Hoa
Bachelor: Nguyen Viet Tuyen
4.
The objects.
ZnO films composed of nanowires and nanorods were fabricated
on the Si substrates
willi
Pl
"tape"
electrodes by the vapor - phase
transport method. The humidity sensitive characteristics of the films
have been investigated. These nanoslructured films show humidity
sensitivity, good long-term stability. It was found that the resistance of
the films decreases with increasing relative humidity (RH). It is reliably
believed that the ZnO nanomalerial films will be used as efficient
humidity sensors.

5.
The content of research.
ZnO has a direct bandgap
of
3.37 eV and high mechanical and thermal
stabilities at room temperature. One-dimensional nanostructured ZnO
materials have recently stimulated great interest due to their importance in
basic scientific research and potential applications in numerous areas such as
nanoscale electronic and photonic. The traditional approaches to synthesize
one-dimensional ZnO nanostructures are the vapor - phase transport process
with the assistance of metal catalysis, thermal evaporation and template -
assisted growth [1].
The humidity control is essential for various fields of industry as well
as human life. In this work, ZnO
films
composed of nanowires and nanorods
were fabricated, respectively, on the Si substrate by the vapor - phase
transport process, and their humidity sensitivity characteristics have been
investigated.
6. Results:
1/Tran
Thi Quynh Hoa, Ta Dinh Canh, Nguyen Ngoc Long, Nguyen Viet
Tuyen,
"Zinc
oxide nanostructure for humidity sensor", VNU Journal
ofScience,
Mathematics - Physics, 2006 (in press).
2/Ta Dinh Canh, Nguyen Ngoc Long, Nguyen Viet Tuyen, Tran Thi
Quynh Hoa, Cao Van Tuan, "Multiform ZnO nanostructures
fabricated by vapor-phase transport method without catalyst", VNU

Journal
ofScience,
Mathematics - Physics, 2006 (in press).
3/
Tran Thi Quynh Hoa, Ta Dinh Canh, Nguyen Ngoc Long, Nguyen Viet
Tuyen and Nguyen Duy Phuong, "Photoluminescence of ZnO
nanostructure prepared by catalyst- assisted vapor-liquid-solid
technique", Tuyen tap bao cao hoi nghi khoa hoc quang pho toan
qu6c \kn
thu IV, Can Tho, 8/2006, (da nhan in).
7.
Conclusion
* Obtaining the aims of the project,
* Training 2 graduate students, 2 master student.
MUC
lUC
Mdddu:
1
Chuang 1: Phuang phap che tao cau triic nano mot chieu
tijr
pha
khi
2
LI.
Cac phuang phap che tao ZnO nano
7.7./. Phuang thuc top - down
7.7.2. Phuang thiic bottom - up
1.2.
Ca che phat trien day bang phuang phap boc bay nhiet dan gian
1.2.1 Ca che hoi -

ran
(VS)
,
*
^
L2.L
Co che hai - long - ran(VLS)
7.2.2 Hien
tugng
can bang nhiet dong
Ciurang 2: Thuc
nghiOin
7
Chuang 3: Ket qua va bien luan 12
Ket luan: : 19
L5i
cam an: 19
Tai lieu tham khao: 20
Md DAU
Hien nay tren the gidi da va dang
hinh
thanh mot nganh khoa hoc va cong nghe
mdi,
CO
nhieu trien vong va
dir
doan se co nhirng tac dong manh me den
ta't
ca cac
ITnh

vuc khoa hoc, cong nghe, ky thuat cung nhu ddi song kinh te-xa hoi
a
the ky 21. Do la
Khoa hoc va Cong nghe nano.
Ky thuat nano la mot khdi dau quan trong ciia khoa hoc ky thuat the ky 21. Theo xu the
chung, ky
thuSt
nano da chd nen
vucrt
troi
hem
trong
cuoc
canh tranh khoa hoc.
Linh virc
nay kham pha nhung
vAl HCii
vl\
li'nh chA'l
cua nd khi
kfchllurdc inftl chiCu
nho cd tu
inftl
idi
vai
iram
nano met, che do
kich
thudc nay duae ndi tdi nhu la
kich

nano (nanoscale).
C)
kfch thudc nano, hieu ung giam gui luong tu
bdt
dau anh hudng tdi tinh chat cua vat
Heu. Cai gi tao cho vat lieu nano su quan
tSm
dac biet, va cai gi da
dan
den su bung no
nhung nghien cuu trong
linh
vuc nay, nhung vat lieu nay cd the
nSng
cao va thay doi
tinh
chat nhu do chung cd su giam gui
lugng
tu trong mot, hai, hoac ba chieu.
Nghien cuu trong
linh
vuc nay se cung ca'p hau het nhung phat minh trong ky
thucU,
Kha nang de lam viec vdi nhirng nguyen tu d
kich
thudc nano, va vdi nguyen tu xac
dinh, huu hen md ra mot
linh
vuc mdi
ciia

su phat trien ky thuat. Tfnh cha't huynh quang
phu thuoc kfch thudc cua
eham luoiig
tu va do
bdn
ra't
Idn
cua ong nano cacbon la hai tfnh
chai cua vat Heu nano ma da cho tieng xau tren mot thap ky qua. Tuy nhien, nd khong bat
dau
xam
pham mot
linh
vuc rong
Idn
cua be mat va quan tam nhung ca'u true va nhiing
tfnh cha't da dugc kham pha.
Linh
vuc nay dugc
hinh
dung lam thay doi
hiu
het moi vat,
lam
thd'
nao chiing ta
ch6'
tao va
liep
can ky thuat. Nghien cuu vat

lidu
nano da thu dugc
Igi fch
tir
trandilo phat xa trudng
(FETs)
cho nhung thiet vi dien
tii
nhd
ban,
nhe han, va
nhanh hon. va
cCing
md ra m()t
linh
vuc mdi gidng
nlur
spintronic.
Tuy
nhiCii,
khoa
ligc nano
va ky
thuAl
nano
vAn
Hong giai doan
clAu
phat
tridn.

Nhung khai
ni6m
co sd chi phdi
linli
vuc nay khdng dugc
hic'u
dAy du va cAn
(Urge kiiam
plui
xa hon. Trong thuc
td',
mot khdi lugng nghien cuu trong
linh virc
n^y
hudng tdi viec
lao ra
bfen
canh nhung kham pha
Idn
trong tfnh cha't mdi, cA'u
true
rifing,
hoac che tao thiei
bi thuong mai bang each su dung nhirng ca'u triic nano nay. Tuy nhien neu khoa hoc va ky
thuat nano bao gid tao ra mot anh hudng
d^y
y
nghia
trong khoa hoc cgng dong va the
gidi rdng Idn, nhung khai niem co ban va

ly
thuyei chi phdi mot ldp rieng cua nhung vat
lieu nay phai dugc phat hien.
Nghien cuu phai dugc tAp trung hon va
ihAin
dd trong
ccrch^kiCm
soat nhung
tinh
chat va
sir
phat trien rieng biet cua nhirng
cA'u true
nay. Chung ta phai luu y
kl
dc' hieu
nhung phat hien dang kinh ngac nay; chiing ta phai khao sat, do, va md hinh, nhung quan
trgng hon, chiing ta phai cd khd nang du doan.
CHl/ONG
I
PHirONG
PHAP
cut
TAO CAU TRUC NANO
1-CHIlSUTirPHAKHI
1,1.Cac
phirong
phap che tao ZnO nano
Cdng nghe
chS

tao nano thudng dugc
tiSn
hanh theo hai phuong thuc la phuong
thuc "tu dudi len" (bottom - up) va phuong thuc
"tir
tren xudng" (top - down). Trong
phuang thuc bottom - up, ngudi ta
lap
ghep nhung hat cd kich thudc co nguyen tu, phan
tu hoac cd nano
dk
tao ra cac vat lieu kfch thudc nano. Trai lai, trong phuong thuc top -
down, ngudi ta chia nhd mot he thdng
Idn
de nham tao ra dugc cac vat lieu kich thudc
nano cd cau tnic va tfnh chat mong mudn.
Vat lieu cau
true
nano
i
^0
^
sap
xep cac nguyen
tir
Chia nho vat lieu
Dhan tu ca nano
khfti
han
rlan

Hmh
1.10:
Phuang thuc bottom-up va top-down
/.2.
/
Phuong
thuc top -
down
I)Ai
vdi cdng nghv
naiu>,
dc
\i\n\
dugc
nhiYng
kich tlnrdc nhd cd I
nni -100
nm,
ngirdi ta phai khac nano bang chum electron, chum ion hdi lu, chum tia X Cd
nh&ng
trudng hgp can kich thudc cd nguyen
tii*,
ngudi ta phai dung bg quet d thiet
bj
hien vi de
quet dau dd dieu kien mui nhgn ve theo cac hinh mong mudn, diing dien trudng d dau dd
de lay di hoac them vao cac nguyen
tii.
Nhiing
each

khac hinh ndi tren khdng the dua vao
san xuat rdng rai vi ton thdi gian va gia thanh kha cao.
Ngoai ra, phuong phap nghien bi cung rat hieu qua trong mgt sd trudng hgp tao
bgt nano. Ngirdi ta chon
ciic
hdn bi cung, to va
nSng
cho vao mgt
cai
trdng hinh
lri,i,
cung.
Vdi tdc dp quay thich hgp, ta cd the thu dugc vat lieu vdi kich thudc mong mudn. Tuy
nhien thdi gian nghien bi cd the keo dai den hang chuc, hang tram gid. Hon
niia,
trong
phuong phap nghien bi vat lieu rat de bi bien dang va cd nhieu sai hdng nen sau khi thu
san pham phai cd qua trinh xu ly thich hgp.
1.2.2 Phirang thuc bottom - up
Phuong phap hien dai nhat cua
viec sap
xep lung phan tu nguyen lu la phuang
phap
epitaxy.
Phirong phap nay cd the khdng che chinh xac thanh phan hda hgc cung nhu
cau
true
vdi kich thudc cd vai nguyen
tii.
Epitaxy la phuong

phap
hieu qua rat cao nhung
ton kem do
sir
dung chan khdng sieu cao.
Ngoai ra, cac
phuoiig
phap hoa hoc khac ciing dugc coi la phuong thiic bottom -
up.
Cac phuong phap hda hgc cd nhieu
hiia
hen vi gia re, che tao dugc sd lugng
Idn
va cd
thS di6u khiSn
kich thudc chinh xac. Ban chat
ciia
viec hinh thanh cac cau tnic nano theo
phuong phap bottom - up chinh la qua trinh tinh the hda thdng qua hai budc co ban: tao
mSm va phat
triSn.
Khi ndng do
ciia cdc
khoi vat chat (nguyen
tir,
ion
hoac
phan tu)
dii
cao,

chiing s6 lien tuc ket hgp lai thanh
nhQug
dam nhd (hay mam) thdng qua
nhijng
nhan
ddng nhat. Sau dd cac mam nay se ddng vai trd lam hat nhan cho cac qua trinh phat trien
tiep theo de hinh thanh cac cau tnic
Idn
hon. Mgt sd phuong phap hda hgc hay dugc
sii
dung de che tao vat lieu cd
cau
tnic nano nhu: lang dgng
tir
pha hoi (CVD) hoac tu pha
hoi
ciia
cac hgp chat
hiJu
co kim loai (MOCVD), phuong phap bdc bay nhiet, bdc bay
bang laser, phuang phap
sol
- gel, aero - gel, phuong phap thuy nhiet
(hydrothermal
method), dung mdi nhiet (solvothermal method)
Mdi phuong phap deu cd
nhiJng
uu diem va nhugc diem rieng. Trong dd, lang
dgng tu pha hoi la phuong phap phd bien nhat trong viec lang dgng cac mang ZnO cau
tnic nano mgt chieu.

LTU
diem
ciia
phuang phap nay la co che don gian, tdc do lang dgng
cao,
mang cd do day ddng deu, cd the dieu khien dugc kich thudc. De che tao hon hgp
hoi Zn va 0 trong phuang phap lang dgng tu pha hoi ngudi ta cd the thuc hien mgt sd
each
sau:
Phuang phap phan
hiiy true
tiep ZnO
rSn
thanh hoi Zn va
O
ZnO
(ran)
>
Zn
(ho,)
+O2
(hai) (
1
•
14)
Day la phuong phap dan gian, tuy nhien nd cd han che
la
nhiet dd che tao phai
cao
(^1400

°C).
Phuong phap nung bdt Zn cd thdi khi oxy. Phuong phap nay la phuang phap
true
tiap,
rihiet
do nung tuong ddi
thAp
(500
°C
- 700
°C),
nhirng ti sd giua ap
suat
hoi Zn va
oxy can phai dugc dieu chinh
hel sue
can than de cd the thu dugc cac
cAu
tnic ZnO nano
nhu mong muon. Ngirdi ta dA quan sat
th/iy rAng
s\r
thay ddi
ciia
ti so
nAy
gdp phan lam
thay
d6i Idn dkw mAu sAc ciia
mAng

cflng
nhu dang hinh hgc
ciia cac
cau tnic nano.
Phuang phap gian tiep de tao ra hoi Zn bao gdm epitaxy tu pha hoi cua kim loai
hiju
CO, ma trong dd hgp chat kim loai
hiju
co Zn, vi du nhu
diethyl-zinc,
dugc su dung
vdi luu lugng khi oxy hay
N2O
thich hgp.
Phuong phap hien nay dugc ap dung nhieu nhat
la
phuong phap nhiet cacbon,
sir
d\nig
bgt ZnO
dirge Iron
vdi bgt
('
d5
lam
v(it Ii$u
nguon.
U'u
diem ciia
phuang phap nay

la si,r
xuat
hi^n ciia
C lam giam dang ke nhiet
dp
phan
lu'iy ciia
ZnO.
- Ngoai ra de tang
hi?u
suat cua phuang phap tren ngudi ta cdn cd
th6 sir
dung
xiic
tac (Au, Pt, Ag, Ni ). Chat
xiic
tac nay se tac dung vdi hoi Zn tao thanh hgp kim. Khi
ndng do Zn trong hgp kim trd
nen
qua bao hda thi mam bat
dSu
dugc
hinli
thanh.
DiSu
khien ldp
xiic
tac ta cd the dieu
ki6n sir
hinh thanh day nano ZnO. Co

ch6
phat
triSn
day
nano ZnO cd
xiic
tac thudng la co
ch^
hoi -
Idng
-
ran
(VLS). Trong khi co
chg
phat
trign
day nano khdng cd
xiic tac
thudng la co
chfi
h(yi
- rAn
(VS).
I.2.C0
che
pliAe trien dfiy
hAii^
phuong phap hoc bay
nhiyt
don

giiin
Tiiy
thudc
diSu
kien che tao mau ma qua trinh phat
triSn
day se thdng qua 2 loai
CO
che la co che hoi -
rAn
(VS) va co
ch6
hoi -
Idng
-
rAn
(VLS).
7.2.5 Ca che hai -
rdn
(VS)
Trong
CO
ch^
VS, tinh
thi
cd the hinh thanh true tiep
tir
pha hoi ma khdng can
sir
cd mat cua cac chat

xiic
tac.
Ban diu co
chi
nay dugc cho
la
do cac sai hdng mang, nhung
vi?c
xuat
hi?n
cac
day nano khdng sai hdng da chung minh dieu
nguge
lai. Them vao dd ngudi ta thay tdc
dg phat trien day cao hon loc dg ngung ty tu pha hoi. Co che nay cd the dugc giai thich
la
do ZnO cd
ciiu
tnic dj hudng,
\v\\c
uu
tien lA (0
0 2| -
tryc mA
dgc
tiico
nd
iiAng
lugng
chu

de phat trien tinh the la thap nhat.
Cac
phan
tii*
khi Zn
va ZnO|.x
hap thu
tir cac mSt
khdng
phat trien day se
khueeh
tan len be mat (0 0 2). Tu day cau tnic nano
1
chieu
ciia
ZnO se
duoc hinh thanh.
(a)
00
I
(b)
A
7'
1
w\
I
1
1
1
1

1
\
A
1
1
1
_
1
1
1
-I
|I2I|
I
201
/•7
'
1
1
1
1
1
1
>-
—
n
r
1
\
Hinh
1.11:

Mo
hinh
day nano ZnO phat trien theo co che VS
Trong
CO
che nay, do lugng hoi tdi
vj
trf ket tinh khdng ddng deu nen dudng kfnh
day nano khdng deu va giam dan ve phia dinh.
1.2.2 Ca che hai - long -
ran(VLS)
Khac vdi VS, CO che VLS phat trien tinh the mgt
each
gian tiep thdng qua pha
Idng ciia
kim loai
xiic
tac.
Kim loai
xiic
tac nay phai tro vdi vat lieu can che tao, cd ap suat hoi thap, ddng
thdi cd diem eclectic thap.
Xiic tac nay
cd the la cac chat nhu Au, Pt, Ag, Ni, (trudng
hgp cd
xiic
tac) cung cd the la kim loai
ciia
chinh oxit (trirdng hgp tu
xiic

tac). Trong
cac
mau khdng cd
xiic
lac, Zn ddng vai trd
tir xiic
tac. Hoi Zn dugc khi Ar dua tdi viing
nhi^t
dp thap hon
sg
hda
Idng.
Cdn trong cac mau cd
sir
d\ing
xiic
tac
(chAng
h^n
Au), hai Zn
vA
/nOi.x
tdi
tAc
d\ing
vdi linh the Au
(lining
thai rAn)
[[}o ihAnh
hgp kim (cAc cau lu

khdng hda lan vAo
nluui)
va hoa long.
Gigt chat
Idng
trong ca hai trudng hgp se trd Ihanh dung mdi thich hgp
dS
bat cac
phan tu khf.
ThS
tich
ciia cAc
gigt chat
Idng nay
tang khi lugng hon hgp hoi tang. Tdi khi
chat Idng
trd nen qua bao hda vdi hdn hgp hoi thi mam day bat dau hinh thanh qua phan
bien rAn -
Idng.
Trong qua trinh hinh thanh day, kich thudc gigt hgp kim khdng ddi, gigt
hgp kim
ludn
dugc
day
len phia trudc,
phAn
tinh the dugc hinh thanh dai dan ra vdi gigt
hgp kim d phfa cudi. Khi kcl
Ihiic quA Irinh
hinh thAnh day, gigt hgp kim

dpng li;ii
d cudi
day. Do qua trinh phat trien thdng qua pha
Idng nen
dudng kinh
ciia cAc day
nano
phy
thudc vao
kich
thudc
ciia
giot chat long va khdng thay ddi trong sudt
qua
trinh
ch6
tao.
Hoi Zn va
ZnO|
Hoi Zn
vaZnOu,
1
w
O O
O,
^
P
De Si cd
phii
vang Gigt hgp kim Day nano,

Au - Zn thanh nano ZnO
Hinh
1.12:
Ca che VLS phat trien
day,
thanh nano ZnO tren de co phu vang [3]
L2.4
Hien
tirang
can bang nhiet dgng
Tuong tu nhu ddi vdi
day
nano
Si
trong tai lieu
[31]
cd the md phdng qua trinh
hinh thanh day nano ZnO nhu sau:
cac
nguyen
tii*
khi Zn
va ZnOi.x
bi
khueeh tan vAo
trong gigt chat long. Neu mau
khdng cd
xiic
tac vang, gigt chat long la hon hgp Zn va
ZnO|.x.

Neu mau cd
xiic
tac vang,
gigt chat
Idng sg
la hgp kim Au - Zn -
ZnOi-x.
Khi gigt chat
Idng
dat tdi trang thai qua
bao
hda vdi nguyen
tir
Zn va
ZnO|.x
mam bat dau dugc hinh thanh. Trang thai can bang
nhiet dgng cua vat lieu cd the dugc md
ta
theo cdng thuc:
7rR'dL = —^Sdt
(]
16)
kT dx
^ ^ ^
trong dd D
lA
hC*
so
kluiyech lAii /n
-

ZnOi.x iren
dc
R
hi
bAii kinh tifly
nano
/J la
the hda
ciia
cAc phan tir ZnO
S
= IjrRa
la dien tich
khueeh
tan
a la hang sd mang.
,_ IDa
du
.
Mat khac do bien thien the hda hieu dung
ciia cAc
phan tir Zn -
ZnOi.x
trong
day
nano va tren gigl chat
Idng
dugc tinh nhu sau:
A//
= Aa-r^—'— (M8)

A
trong dd
ACT
la irng suat trong ldp mang Zn - ZnOx
0)
la the tich nguyen tir Zn,
ZnOi.x
y
la nang
lugng
mAl
{v\\
Do bien thien the hda hieu dung
A//
chfnh bang tdng
ciia
hai
phan
nang lugng:
PhAn
nang lugng.dan hdi tren mgt nguyen tir do su phuc hdi
bi6n
dang tren gigt
chAt Idng
AOTy
va phAn nang lirgng mat di tren mgt nguyen tir do su
tAng
dien tich
hk
mat

ciia
day
nano
-^. Ro rang
khi
b^a^lylr
(r la ban kinh gigt
chdt
long
r «i?)
thi
A//
= 0
day khdng phat trien
niia.
p
JUffflMi'ii iTm
\
1
7
^
Dl
>
r
///Az/z
7.75
Md
hinh day
nano
phat trien theo ca che VLS

IJ'ng
sudt xuat
hi?n chii
yeu trong phan gan gigt
vang.
Do
v^y
khoang
cAch ph\ic
hAi
irng
suAl lA
X (hinh
1.13),
khi dd:
di,i tS.^.L
dx
(1.19)
Cuoi Cling
IDa
/ScTCO^
'lr"'Ti7
2r
AaR
(1.20)
Vay chieu dai day ty le thuan vdi thdi gian phat trien / va ty
le nghieh
vdi ban
kinh day R.
Thdng thudng

Aaco
I kT
rAt
nhd nen chieu
dAi
day bj han che dang ke khi khdng
sir dung xuc tac. De tang chieu dai day ngudi ta diing cac
xiic
tac vang. Chinh xuc tac nay
da tao ra hgp kim Au - Zn -
ZnOi-x
tao nen mgt pha
Idng
cd nang lugng hinh thanh mam
thAp
dii dh
phat trien cac day nano.
CHirONG
II
THI/C
NGHI$M
2.7
Phirtmg
phap che tao vat
li^u
Mau ZnO nano day da dugc che tao bang phuang
phAp
bdc bay
nhi^t
don gian.

Ban chAt
ciia
phuong phap
nAy
la
sir
lang dgng vat lieu tir pha hoi. LTu diem cua nd la co
chi
dan
giAn,
tdc dg
lAng
dgng cao,
mang
cd dg day ddng deu, cd the dieu khien dugc
kich thudc.
2.7,7.
Sa dd he boc bay nhiet dan gian [8]
Ld nung
t
Ar
oooooooooooo
Khi
Ong thach
<
cap
nhiet
n
^
B6t

nesi
tZZl CZI C=)
OOOOOOOOOOOO
AT
1
Hinh
2.1:
Sa do he hoc bay va
Id
nung
He boc bay nhiet don gian gdm mgt
Id
nung hinh dng
nam
ngang dai 45 cm va
mgt he thdng
diiu
khiln.
Thdng qua bd
diiu
khien ta cd the lap trinh san che do hoat
ddng
ciia Id
nhu nhiet do khdng
chi,
toe
dg tang nhiet, tdc do ha nhiet, thdi gian dn dinh
nhi?t
Nhi?t
dg cao nhat ma

Id
dat dugc la
1200
°C.
Dd la
nhi?t
dp do dugc d
tam
Id.
Thdng thudng
Id
dugc sir dung d nhiet do
1000
^C.
KhAo
sAt sir
phan bd nhiet
trong
Id
khi rihiet do dugc
giCr
dn dinh tai
1000 T
cho thAy nhiet do phAn bd lech ve phia
trai,
nhiet do tai tirng vi tri tren
Id khA
dn dinh theo thdi gian, sai sd nhiet do khdng qua
10
^C.

NIU
ehgn
gdc tga dg tai tam
Id
thi
s\r
thay ddi
nhi?t
dp
Id
dpc theo
tryc Id
dugc
bilu
dien bieu dien tren hinh 2.2
Ihco bAng s6 li^u lh\rc nghipm
2.1
L (cm)
-22
-21
-20
-19
-18
T{°C)
330
458
570
655
710
Hdng

.
L(cm)
-13
-12
-11
-10
-9
:', /.
I'hdn
T
C'C)
902
922
940
955
969
hd nhlC'l ci()
Ihco
L(cm)
-4
-3
-2
-1
0
TC'C)
1000
1000
1000
998
996

chieu
ddi U)
Z.(cm)
5
6
7
8
9
r(°c)
959
949
930
912
891
L(cm)
14
15
16
17
18
r("c)
756
719
682
640
600
-17
-16
-15
-14

770
810
846
872
-8
-7
-6
-5
977
984
991
996
1
2
3
4
991
984
979
971
10
11
12
13
869
842
815
785
19
20

21
22
549
490
415
330
1200
1000
U
800
-
^'
600
400
200
T
•
»••—"1
•"
frfD
m
&
m
m
ui
m
•
/
BB Nira
16

1
.
1
.
1
—1—
trai
I
1
1
I
1
1
1
1
1
1
1
1
I I
Nira
16
1 1 1
•
'
1
•
1
:
•

ffl
m
m
ffi
ffl
m
phai
a
1 1 1
1
L
-24
-18 -12
12
18 24
•6
0 6
Vi
trf (cm)
Hinh 2.2.
Phdn
ho
nhi^t
do doc
theo
true
cua
Id
2.1.2.
Quy

trinh
che tao
2.1.2.3.
Chuan
hi
Vat lieu ngudn
la bdt ZnO (99,9 %) va bdt C (99 %). Cac bdt
ngudn dugc
can
bang carl chfnh
xAc.
Ty le bdt
ngudn
ZnO:C
tinh theo
moi
thay
doi
trong khoang
tir
1:0,05
den 1:0,2. Hon hgp bdt
ngudn dugc trdn
ky
trudc
khi cho vao
Id.
Vat
lieu ngudn
dugc

cho vao
Ihuyen
sir rdi
dAl
vao
giira
Id (vi tri
cAch
tam 3 cm) noi cd
nhiet
dp cao
nhAt.
Nhiet
do Id
dugc khdng
chi
tai
To
=
1000
T.
Khi dd su
biln
ddi
nhiet
dp
theo
tirng
vi tri
trong

Id
tuan theo
quy
luat
tren hinh
2.2.
Viec chpn nhiet
dp
dl
phu
thudc
vao
each
chpn
vi tri dat de
trong
Id.
Nhiet
dp dl
thudng dugc
ehgn
trong khoAng
tir 500
°C
den
700
""C.
Nhu vay cac dl
dugc
dat d

nira
phAi ciia 16 each
tam
Id
tir
15 din
20 cm.
Toan
bd he
thdng
thuyen
va de
dugc
dat
trong
dng
thach
anh hd hai dAu.
Dc
la cac (am
Silic (100) dirge
rira
.sa
bo
hAng
con.
Trudc
khi lao man dc
dirge
rung sicu

am
U'ong
mdi
Inrdng
axcton khoAng
30
plit'il,
roi say khd
Uii W) "C
trong
Id
say.
\^i!t iiAng
cao
hieu
qiiA clic
lao, sau khi
ihAnh
phan
vai lieu
nguon dugc chon
phu hop,
mdi
ldp vang xiic
tac
mdng dugc
phiin
xa len
tren
bl

mat dl.
Xiic
tac
dugc
ehgn
la
vang
(Au)
vi
hoi
vang
cd ap
suat thap
va tro ve hda hgc so vdi vat
lieu
ZnO ban
dAu.
Xiic
tac nay se
tao
ra mdi
trudng thuan
Igi
de
hinh thanh
va
pRat
trien
cac day
nano.

Trong
qua
trinh
che tao mau cdn cd
sir
tham
gia
ciia
khi
mang Argon
(Ar). Khi
dugc
dua tir
binh
wen
khi Ar
cdng
nghiyp
vao
mgl
dau ong
thach
anh, dAu kia
ciia
ong
thach
anh noi vdi mot
binh
dau
nhdn.

Dua vao
the
tich giot
dau noi
len tlieo
thdi gian,
la
cd
the
linh dugc
luu
lugng
khi Ar qua dng. Tdc dp
thdi
khi
dugc giir khdng
ddi
trong
lAl
ca
cac
qua
trinh
che tao sao cho sd
gigt
dau
xuat hien trong
1
phut
la 60

gigt,
ban
kinh
mdi gigt
la 0,5 cm. Vay luu
lirgng
khi
thdi trong binh
la:
8
v
= 60 ;r.(0,5)^=3K4cmVphut
(2.1)
2.L2.3.
Chetqo
NhiC'l
dg Id dugc dAl
Ihco
chuang trinh
{\x
ddng.
QuA
trinh nung dugc
lhi,rc hi^n
iheo
3 giai doan bieu dien tren hinh 2.3.
U
1200
1000
800

600
:^' 400
200
1 1 1 1 •
/:
/
•
I ill
s
[!) ;
.J
L.
\
III
m
m
m.
ffl,
FU,
' -
•
I 1 I 1 I
100 200 300 400
Thdi gian (phut)
500
Hinh
2.3.
Che do nhiet do nung trong qua trinh che tao
Giai dogn
1:

TAng nhi^^t
lu
nhi?t
dp phdng len tdi
1000 ''C Toe
dg
tAng nhi?t lA
25
°C/
phut,
d nhi?t
dg cao, bgt carbon (C) trong dieu
ki?n thilu
oxy tAc
dyng
vdi oxy
(O2)
sinh ra khf CO (chAt dgc, khdng mau, khdng
miii).
(ran)
+ 0
2 (khi)
/
cao
>
CO
(khi)
(2.2)
Khi nhiet do tang len khoang 400
°C

trong
Id
phat ra anh sang dd, khdi mau
trAng
va
miii
hoi khet.
Cacbon va khi CO se ddng vai trd chat khir tAc dung vdi bgt ZnO sinh ra hoi Zn
va hai
ZnOi.x (thieu
oxy). CAc phan irng cd
the
xay rn hi |7
,13|:
Zll(
)(,fin) ' ^' (inn) -> /^II (hin) '' CO2 (khi)
ZnO(rftn) "^
CO
(kill) ->
Zn
(!,„,)
+ CO2 (khi)
ZnO(ran)
"^
CO(khi)
—> ZnOi-x
(hoi)
"^
C02(khi)
+

o
2 (khi;
850"r
Zn
(khi)
Trong qua trinh nay mam bat dau dugc hinh thanh.
> ZnOi-x (hoi)
(2.3)
(2.4)
(2.5)
(2.6)
Giai
doqn
II: On
dinli
nhivt, khdng
chO nhivl dp
d
1000 ''C
trong
60
phiil.
Trong
giai doan nAy loc do thdi khi Ar dugc khong che khoang 30
cm7phiit.
Viec dieu khien
tdc do khi
rat
quan trgng vi qua trinh
nay

lien quan mat thiet tdi djnh hudng
ciia
cac dAy
nano.
Cac phan irng (2.3) tiep tuc thuc hien. MAm dugc hinh thanh nhieu, qua trinh
phAt
triln
dAy vA oxy hda dAy bat dau xay ra.
Giai
dogn
111:
Ha nhiet, cho
Id
ngudi tu nhien tdi nhiet dg phdng. Trong giai doan
nay, day nano tiep tuc dugc hinh thanh va oxy hda cho tdi khi qua trinh phat trien dAy
dimg lai.
Sir
hinh thanh day nano tren de dugc md ta tren hinh 2.4
Giai doan 1 Ddng Ar
«C)
•
•••. ••
o#«
^•^
o**
^300°C <
^
800
"C
Giai doan 2

Ddng Ar
«o
*
• . •
•
^
•
'k-'^<^-
^
^
'Day ZnO
*****
L6i
Zn
ZnO
-V6^
~300T *
Giai doan 3
- ~800"C
Dong Ar
~
800
°C
Day ZnO
L3i
Zn -V6
'7 r\
~
300
°C **

Hinh
2.4:
Mo
hinh
mo td qua tnnh
hinh
thanh day nano
[15].
10
2.1.2.3.
Thu
san pham
Thdi gian de
Id
ngudi tu nhien tir 1000
°C
tdi nhiet do phdng (30
°C)
la khoAng 4 -
5 h. MAu thu dugc thudng cd be mat kha min. Mau cd mau anh den hoac trang
due
phu
thudc vao che do tao mau, cu the la khi nhiet do de cao mAu thu dugc cd mau
trAng,
khi
nhiet do de thap mAu cd anh den. Mau sac
ciia
mau dugc quyet dinh bdi do day
ciia
ldp

ZnO tren de.
I linh
2.5: Mau sau khi
che
tao
CHUONG
III
KJ^T
QUA VA BI$N LUAN
3.1.
Ket qua phan tich cau
triic
ChAt lugng mgt mau phu thudc rAt nhieu
vao
cac thdng sd che tao nhu thanh phan
vat
li^u
ngudn, chat
xiic
tac,
nhi^t
dp, Cac thdng sd ve ty
1^
moi
giua cac
v^it
li?u
ngudn,
dO
dAy Idp vAng

phii livn
dc,
nhitjt dO dl
dugc thay ddi dl lim
vi\
chi
dd
tAi
uu cho
quA trinh tao mau ZnC) nano day. Dua
vAo
cAc
kit
qua phan tich cau tnic la cd the lim
dugc
CO
che hinh thanh va phAt trien
cAc
day nano ZnO.
Trong CO che VLS, hoi kim loai Zn se ddng vai trd tu
xiic
tac. Hoi kim loai nay
dugc khf Ar mang den vimg cd nhiet do thAp hon va ngung tu thanh gigt. Gigt chat
Idng
Zn trd thanh dung mdi thfch hgp hAp thu hdn hgp hoi Zn va
ZnO|.x,
hinh thanh mAm va
phat trien thanh dAy ZnO. Tuy nhien kha
nAng
hinh thanh dAy nano theo co che VLS

trong trudng hgp
[\r
xiic
tAc
lA
thap. MAm tinh the trong cA hai co che deu ty le vdi lugng
hoi Zn,
ZnOi-x.
Lirgng hoi nAy lai phu thupc vAo lugng carbon. Do vay sd lugng va hinh
dang
ciia
dAy phu thudc vao lugng carbon. Khi lugng carbon trong bdt ngudn nhd (hinh
3.1 a), sd lugng
niAni
quA it, sd lugng dAy tinh the dugc hinh thanh khdng dang ke, chung
phAn bd khdng deu tren de. Khi lugng carbon qua Idn, sd lugng
vA
kfch thudc mAm
Idn
dAn den mat do va kich thudc cac tinh the
Idn
(hinh 3.1 d). Qua trinh oxy hda trong cac
thanh nano cd kfch thudc
Idn
nay
xay
ra khdng hoAn loan. Do dd trong
loi
thanh vAn
Idn

tai kem. Thanh nano se cd cau
tnic Idi
vd vdi loi la Zn
va
vd la ZnO nhu cau triic thu
dugc trong [27, 29]. Dieu nay
phii
hgp vdi su xuat hien dinh nhieu xa
dAc
trung cho tinh
the Zn quan
sat
dugc tren hinh 3.2 d. Ngoai ra, lugng mAm
Idn
cdn gAy bat Igi cho qua
trinh tao tinh the. Bdi vi lugng mam
Idn,
Ap suat hoi tang, xac xuat hinh thanh sai hdng
tang, kha nang hinh thanh
mam
thir cap tang,
day
tinh the khdng cdn d dang don tinh the.
Vay thdng qua viec phan tich
cau
tnic, ta thay
day
nano trong
cac mau
khdng cd

xuc tAc
vAng
cd the hinh thanh theo 2 co che
la
VS va VLS. Ty le carbon trong vat lieu
ngudn cd mgt vai trd
xiic
tac rat quan trpng. Lirgng carbon tAng thi lugng day nano cung
lAng.
Khi lugng carbon Idn, cAc mau thu dugc la cAc thanh nano da tinh the cd kich thudc
Idn,
trong mau van cdn thanh phan Zn do chua oxy hda het. Ty le
ZnO:C
thich hgp nhat
cho viec hinh thAnh day nano ZnO
IA
1:0,15.
3.1.1.
Anh
hwang ciia
chieu day lop
xiic
tdc vang tren de
Tir ket qua khao
sAl
cau triic theo ty le bdt ngudn ta chpn thanh phan bdt ngudn
1:0,15
cho tat ca cac mau che tao. De dieu kien
sir
hinh thanh va phat trien day nano,

trudc khi che tao mau, de dugc plui Idp vAng vdi chieu day khac nhau lir 20 nm den
100
nm. CAc man
ircn
de plui vang
deu
dugc che
li^io
d che do
nhi(Jl
dd dl 7' - 600
"C,
tdc dp
thoi khi
V ' 31 A cm*/plnil \'A
(rong thdi gian /
^=
I h.
Anh
SLM ciia
cAc mau nAy dugc bieu dien
trcMi
hinh 3.3. Ddi vdi tat ca cAc mau,
cac dAy dugc
sAp
xep cd trat tu hon so vdi cac day trong mAu tren de khdng
phii
vang.
Tuy nhien chung chua dinh hudng dugc hoAn toan theo mot phuang xac dinh. Chieu day
cua mang Au tang thi dudng kinh

ciia cac
dAy cung tang theo, ddng thdi chieu dai
ciia
cAc
dAy giAm. Khi chieu day Idp mang la 20 nm va 25 nm thi day dai vai |im, cd dudng kinh
trung binh cd 36 nm va 40 nm
tuxyng
irng. Khi
chieu
day ldp vang
len Idi
50
nni,
cac cau
12
tnic nano thu dugc cd dang day dudng kinh
Idn
cd 60 nm. Chieu day ldp
vAng Idn
nhat
dugc khAo sat la 100 nm. Khi dd tren mau thu dugc
cAc
thanh ZnO ngan
va
cd dudng
kinh cd
130
nm.
DI
tim

hieu ky hon co che phat trien
cac
dAy nano, la se quan sat Anh SEM tai dAu
mill
ciia
cac day nano tren mau cd Idp vang
lA
50 nm.
I Mnh
3.4
lA
Anh SEM
ciia nipt
day
nano
Ifm
ciing
Ui
mgl gigl chat Idng cd dirdng
kinh
50 nm.
Hinh
3.4: Anh SEM cua mau ZnO che (ao vai
d()
day lop vdng 25 nm
Phd nhieu xa tia X
ciia
cac mau ZnO che tao tren de cd Idp vAng khac nhau dugc
chi ra tren hinh 3.5. Trong cac mau ngoai pha
luc

giAc
ciia
ZnO cdn xuAt hien them pha
vang vdi hai dinh
(III)
va (2 0 0). Chimg td trong mAu thuc
sir
cd vang. Trong phd
XRD
ciia
cAc
mau cd Idp vang day cung thay xuAt hien dinh dac trung cho tinh the Zn.
Diiu
nay cho thAy trong cac mau cd tinh the
Idn
vAn ton tai pha Zn.
Hinh
3.5:
Pho XRD
ciia
cdc mau ZnO che tao tren de cd phu lap vdng
vdi
d()
ild\'
khdc nhau:
(a)
20 nm,
(b)
25 nm, (c) 50 nm, (d)
100

nm
Cac
kit
qua phan tich cau tnic
trcMi
day vA dAc
biet
la
sir xuAl
hien giot hinh cau
tai cudi
ciia
day nano nAy la mot bAng chirng rd rang ve qua trinh
phAt
trien day dua tren
CO chi
hoi -
Idng
- ran (VLS ) [29, 30]. Ban
dau xiic
tac vang d trang thai ran. Sau dd
xiic
tac nAy
lAc
dung vdi hdn hgp hoi Zn vA
ZnO^x
d nhiet dp cao tao nen hgp kim Au - Zn -
ZnOi-x.
Hop kim nay cd nhiet do ndng chAy thAp hon nhiet do ndng chay
ciia

vang.
d
nhiet do cao, hgp kim hda
Idng
va trd thanh mdi trudng thuan
Igi
(dung mdi) hap thu hon
13
hgp hoi Zn va
ZnOi.x.
Khi lugng hoi hap thu tang, the tich gigt chAt
Idng
tAng. QuA trinh
nay dimg lai khi chAt gigt
Idng
trd nen qua
bAo
hda vdi hon hgp hoi Zn
va
ZnOi-x-
Liic
nay mAm mdi bat dAu dugc hinh thanh va phat trien thanh day ZnO (the ran).
Trong sudt qua trinh phat trien, gigt hgp kim vang lien tuc bi day len. Do dd dinh
tinh the Au xuat hien trong tAt cA cac phd XRD (hinh 3.5). Hon the, the tfch gigt hgp
kim
vang khdng bi thay ddi trong quA trinh phat trien dAy nen dudng kinh day hAu nhu khdng
thay ddi trong sudt quA trinh che tao. Vay kfch thudc va vi tri gigt hgp kim vAng se quyet
dinh kich thudc va vi trf cac dAy nano. Do day ldp vang
eang
Idn,

kfch thudc gipt hgp
kim
eang Idn
dan tdi kich thudc dAy
eang
tang (hinh 3.3).
Khi dp day ldp vang la
Idn
nhat (hinh 3.3 d), mau thu dugc chi tdn tai cac thanh
ZnO nano vdi dudng kinh
Idn
va chieu dai nhd. Chieu dai ty le
nghieh
vdi ban kinh day.
Dieu nay hoan loan
phii
hgp vdi cdng thirc ly thuyet (1.20) da trinh bay trong chuong I.
Phd XRD
ciia cac mau
cd cac thanh nano dudng kinh
Idn
deu xuAt
hi?n
dinh dac trung
cho tinh the Zn chirng
Id
qua trinh oxy hda xay ra chua hoan loan.
Nhu vay ket
qiia
thuc nghiem mot

lAn nira
khang djnh rang co che phat trien day
nano tren de cd
phii
vang
la
co che VLS. Trong qua trinh hinh thanh mau, vang phu tren
dl tham gia vao gipt hgp kim va ddng vai trd
xiic
tAc. Dp day ldp vang quyet dinh kich
thudc tinh the ZnO. Dp day ldp
vangcAng
Icin,
thiet dien
day
ZnO nano
eang Idn
va
chieu dai day
eang
nhd. Tinh the dAy ZnO kich thudc
Idn
thudng du kem do qua trinh
oxy
hda khdng hoan loan. Vay chieu day tdi uu
ciia
ldp vang thich hgp cho day nano phat
trien
la
trong khoAng tir 20 nm den 25 nm.

Tdm
Kii,
thdng qua
vi^c
chpn ty
1$ bpl
nguon thich hgp vA sir
d^ing
dl cd plui
mpl
Idp vAng mdng, ta cd the dieu kicn dugc kich thudc day nano. Tuy nhien
sir
dinh hudng
vA djnh vj
ciia
cac day nano
liii
chua the dieu khien dugc bAng
each
sir dung dc
phii
vang
nay.
3.2. Pho huynh quang nhiet do thap cua day ZnO nano
Mgt trong nhung irng dung
ciia
vat lieu ZnO cd cau tnic nano la cd the sir dung
chimg trong cac linh kicn quang
dipn
tir. Do do nghien ciru linh chat huynh quang

ciia
cac mau nhan dugc la can
ihict.
Cac quy luat bien thien
ciia
nAn^
lugng huynh quang
Ihco
nhiet dp do
mfiu sO
cho la
nhieu
thdng sd quy bau
\\c\\
quan den cAu tnic vimg
nAng
lugng
ciia
loai vat
lieu
nay. De hieu rd bAn chAt
ciia
cAc dinh huynh quang, mau ZnO tren
dl
phii
ldp Au day 20 nm da dugc do huynh quang tai nhiet do thAp. Cac phd huynh
quang dugc do trong dAi nhiet do tir 14,5 K den 300 K, sir dung budc sdng kfch thfch
X =
300 nm.
i.2.7.

Cache
tdi hap
ciia
huynh quang mien khd kien
Tren hinh 3.9 la tap hgp cAc phd huynh quang
ciia
mau.
6
mgi nhiet dp, trong phd
huynh quang deu quan sat dugc mot dai
phAt
xa rdng keo dai tir dai mau xanh da trdi
din
xanh la cay vdi tam nam tai 2,5 eV va mot nhdm cac dinh tir ngoai (UV) hep. Dai huynh
quang xanh da trdi - xanh la cAy thudng dugc
gAn
vdi co che tai hgp
hire
xa qua cac mirc
sau
(nut khuylt oxi, nguyen tir kem dien ke),
cac
trang thAi bay
hoAc
cAc trang
thAi
bl
mat. Cac gia thill ve cac co che dd thudng dua tren co sd ZnO la mgt oxit khdng hgp
thirc.
Cac mirc nAng lirgng tao ra

lidi
cac loai sai hdng nhu mil khuylt oxi
{V^^),
nguyen
tir kem dien
kS
Zn,'\
mil khuyet oxi bj ion hda
(KJ
), nguyen tir
kgm diln
ke bi ion hda
Zn
'^
Zni'"".

cd the
ion
tai trong vung cam
ciia
ZnO
[20],
14
1.8x10
^
1.5x10"
-
1—I—f—I—I—1—1—I
1 r
^uvt

^^-j
2.2 2.4 2.6 2.8 3.0 3.2
Nang lugng (eV)
3.4
Hinh
3.9: Pho huynh quang nhiet
dg
thap cua mau ZnO nano day
Tir hinh 3.9 cd the thAy ro dinh tai 2,5 eV rdng
va
hau nhu khdng thay ddi vi tri
khi nhiet dp thay ddi. Nhu vay dua theo quan diem
ciia [21 ]
cd the cho
rAng
day la td hgp
cua nhieu qua trinh chuyen mirc dugc chi
ra
tren gian dd nAng lugng hinh 3.10 nhu
:
Vy~
->
V-^^
irng vdi 2,2 eV,
Zn^
->
K;,
irng vdi 2,32 eV,
V^;;
->

VB irng vdi 2.8 eV.
Vinui
dan
.y,
•
1
\
2.:
2.8
:
1
2.2
r
I—
3.13
3,3
1
IDA
113
3.3f
BF
D°}
t
Vime
hda tri
Hinh
3.10:
Mo hinh cdc
mice
dien tu trong ZnO

3.2.2. Ca che tdi hap cua huynh quang mien
ti^
ngoai
[15]
x38
x7Q0
14.5 \L
X
190
37.1
K
61.6 K
X 13
iiLLK-
Nn.5 K
X
2.6
190.8 K
X
1.3
250.4
K-
300.0 K
3.0
3.2 3.4 3.6
Nang lugng (cV)
3.8
Hinh
3.11:
Pho huynh quang nhiet do thap cua mau ZnO nano day

IS
,
r
« *
Viec giai thich ngudn gdc cua cac dinh mien tir ngoai trong phd huynh quang
ciia
ZnO dugc nhieu nha nghien
cim
quan tam, tuy nhien cd nhieu y kien khac nhau ve co
che phat quang. De khao sat ky han ve co che huynh quang mien
cue
tfm, dai phd tir 2,8
eV
din
3,8 eV cua mau ZnO do trong dAi nhiet do tir 15 K
din
300 K dugc chi tren hinh
3.11.
Cd the thay rang d
nhi^t
do thap, tai mien huynh quang tir ngoai, trong
cac
phd
deu xuAt hien 4 dinh. Tuy nhien do tuong quan cudng do phd nen cac dinh cd the
ehdng
chap nhau. Tai nhiet dp 61,6 K
sir
tach phd tu nhien cd the quan sAt tdt nhat. Hinh
3.12
bieu dien phd huynh quang tai nhiet dp nay.

Phd huynh quang nhiet dp thAp vimg tir ngoai gdm 4 dinh: mot dinh tuong ddi
rpng tai
3,113
eV (dinh IV) va 3 dinh
h?p
(III, II, I) tai 3,243 eV, 3,316 eV,
3,362 eV tuong irng. Khi
nhicl
dp tang len,
cAc
dinh nAy bj
djch
ve phia nang lugng
thap
Irong khi cudng dd
ciia
cluing giAm di. CAc dinh 1,
II,
111
khA
h(?p
vA cd nAng lugng rat
gAn
vdi nAng lugng viing cAm nen chung cd the dugc
gan
vdi co che tAi hgp exciton.
Dinh I bien mAt khi nhiet do xAp xi
166,1
K trong khi hai dinh (II, III) tdn tai tdi tan nhiet
do phdng.

5x10-
OX}
c
cr
j=
c
'>»
3
-O-
I
4x10
3x10"
2x10'
-
1x10
I
' I
*
I ' I '
1
o
S0ll^ulhvcnghlCmtlolal6l,6K
" Dirdng
nt
long Ix/p
Kit dinh
I,
II.
III.
IV

-
_
.
1 1
.
I
.''t.A.
•
1
3.362 -
D'X
1
3.3
!6|
BF
1
3.316
BF-LO
3.113
DAP
1
II
1**1
Z'-
-1
2.4
2.6
2.8 3.0 3.2 3.4
Nang lugng (eV)
Hinh

3.12:
Phd huynh quang
ciia
mau ZnO nano day do tai nhiet do
61,6
K
De
lAm
sang td ngudn gdc cua cAc dinh phAt xa nay, cAc sd
lieu
thirc nghiem dugc
fit bdi hAm ddi xirng Pearson
Vll
(vdi dg tin cay > 99.3 %)
[14],
y
=
A
2Vm.e^'^
-"
nWe
r(m-0.5)
1
+
4 : '- - ^
W
{X-Xr)
•m
(3.1)
trong dd A

lA
cudng dp tfch phan, W
lA
ban do rdng (FWHM), m la he sd hieu chinh,
xc la
Ipa
dp dinh, and V la hAm dugc
xAc
djnh bdi:
\a)^\t"
\l( {a '{))
(3.2
Sir dung ham (it (3.1) cd the tach tirng phd thanh cac dai thanh phan vdi cAc dinh
tuong irng
phii
hgp. CAc phd thanh phan
ciia
dAi huynh quang
cue
tim tai 61,6 K cung
duoc bilu dien tren hinh
3.12.
Tir cAc
kit
quA fit la cd vi trf dinh, cudng dp tich phAn vA bAn dp rdng
ciia
cac
dinh UV. Dua vAo cAc sd lieu nay ta cd the xAc dinh dugc ngudn gdc cua cAc chuyen ddi
dien tir phat ra tin hieu huynh quang. Tren hinh
3.13

lA
dd thi bieu dien
sir
phu thudc cua
nang lugng cac dinh pho I, II, III, IV vao nhiet do.
Cd the thAy rd rang cAc giA tri thirc nghiem
ciia
dinh I kha
phii
hgp vdi cdng thuc
Varshni [28]:
E{T)=I':{Q)-^—
(3.3)
trong dd £(0) la
nSng
lugng irng vdi vi tri dinh tai 0 K
a wk /3
la cAc tham sd thuc nghiem
100
160 200 250 300
350
Nhiet do (K)
Hinh
3.13:
Sir
phu thuoc cua ndng lirang dinh vdo nhiet do
Dua vao cAc sd
lieu
fit dugc ta cd the tinh toAn
a

= -9,8x10 eV/K ,
J3
= -800 K vA
E(0) =
3,369
cV. Tir hinh 3.13 la thay vj tri dinh
1
cd nAng lugng Idn,
phii
hgp khA tot vdi cdng
Ihirc
Varshni. Dinh I bj dap
lAl
d nhiet dp
166,1
K. Do vay dinh
I cd
thi lA
tai hgp
ciia
exciton lien ket vdi donor trung hda.
Dinh II va dinh III van tdn tai d nhiet dg phdng va vi tri dinh giAm theo nhiet dg
eham
hon so vdi nang lugng viing
cam.
Dinh phat xa II da dugc nhieu cdng trinh bAo
cAo.
Tuy nhien ngudn gdc
ciia
nd cdn

lA
vAn de
phAi
bAn luan. Mgt sd tAc giA cho
rAng
dinh
phAt
xa nay
lA
exciton lien
kit
vdi acceptor trung hda [18, 19, 26, 32, 33]. Mgt sd tAc
giA
khAc
l^i
cho rang dinh nAy
lA
do
svr
chuyen ddi hai
di?n
tir
ciia
exciton lien
kit
vdi
donor trung hda
[18,
28], do
lAi

hgp
ciia
exciton lien ket vdi acceptor trung hda [19, 33]
hoac do cAc cap donor - acceptor [32]. Tuy nhien
chiirig
tdi ddng quan diem vdi cac tAc
giA
[11]
cho rang su phAt xa nay khdng the
la
su chuyen ddi hai dien tir
ciia
exciton lien
kit
vdi donor trung hda, cung khdng the
lA
tai hgp cua exciton lien ket vdi acceptor trung
hda vi hai loai tai hgp nay bi dap tat d nang lugng thap, khdng tdn tai tdi nhiet dp phdng.
MsAl
khac vi cac vach nay
h<^p,
vA giAm rAt
eham
theo
nhipt
dp nen khdng
thi
la
pliAt
xa

do tai hgp
c^lp
donor - acceptor (phan tich ve
lAi
hgp cAp donor - acceptor se dugc ndi rd
d phan sau). Cd the dua ra gia
ihict
rAng dinh
II lA lAi
hgp
ciia
hat
lAi tren
tap chAt vdi mpl
hsil lAi Ur
do (Bound -
I'rcc
Bl'). Mau ZnO dugc
che
tao
lA
ban dan
lo^ii
n
nen
dinh II cd
thi
la dien lir lien
kit ircn doiu)r
lai hgp vdi lo trdng lu do trong viing hda

trj.
Chuyen
ddi
17
OAI
HOC QUOC
GiA
HA
NQ*
TRUNG TAM
TNONG
TIN
THQ
VIEN
ZEZOZZ
nay
ciing
dugc nhieu tAc giA quan sat thay trong ZnO ca d nhiet do thap
va
nhiet do
phdng.
KhoAng
each
nAng lugng
giOa
hai dinh II va III ludn
lA
73 meV. KhoAng cAc nay
xap xi dp dAi phonon quang dgc. Do dd dinh III cd
the lA si,r

l^p
l*;ii
phonon
ciia
dinh II
(BF-LO).
DAi phd rdng cudi ciing (dinh IV) giAm rAt nhanh khi nhiet dp tAng. Dinh nAy dugc
giAi thich
lA
do
sir
tAi hgp phAt xa
ciia cAp
donor - acceptor (DAP). Nang lugng irng vdi
vi tri
ciia
dinh nay dugc xAc dinh theo cdng thirc (1.9):
hco
=
AE
-E^ -E^
+-
d nhi?t
do thap cac hat
lAi
tren donor va acceptor vdi khoAng
each
r nhd s5 bj tai
hgp trudc, nAng lugng phAt xa
Idn.

Khi nhiet do tAng len cac hat tAi tren donor va
acceptor vdi khoAng cAch
Idn
hon se bi tAi hgp, nang lugng giam dan. Ket quA
lA
dinh
DAP djch nhanh ve phia nang lugng thap khi nhiet do tAng len.
Nhu vay bang viec phan tich dd thi
sir
phu thudc nAng lugng dinh huynh quan