Chế tạo và khảo sát tính chất của lớp chuyển tiếp p-n trên cơ sở màng mỏng ZnO và khả năng ứng dụng của chúng

DAI HOC
QUdc GIA
HA
NOI
TRUdNG
DAI HOC KHOA HOC
TU NHI^N
•
•
• •
•
«
•
CHE TAO VA KHAO SAT
TINH
CHAT CUA LOP
CHUY^N
TI^P
p-n
TREN CO
SO MANG
M6NG ZnO VA KHA
NANG
UNG
DUNG
CUA CHUNG
Ma
so:
QT -
08
- 16

CHU TRI
D£
TAI:
PGS. TS. Ta Dinh Canh
CAC CAN BO THAM
GIA:
CN.
Nguyin
Viet Tuyen
HA
N6I
- 2008
BAO
CAO
TOM TAT
De tai:
CHE TAG VA KHAO SAl TJNH CHAT CUA LQP CHUY^N
TI^P p-n TREN CO Sd
MANG
M6NG
ZnO VA KHA
NANG
UNG
DUNG
CUA CHUNG
Ma so: QT - 08 - 16
Chu tri de tai: PGS. TS. Ta Dinh Canh
Can bo tham gia: CN. Nguyin Viet Tuyen
1.
Muc tieu de tai:

Trong cac hop chat ban dan, ZnO la chat ban dan c6 do rong
vomg
cam
Ion
(-'3,3eV
a nhiet do
phong),
do ben vung va nhiet do nong chay cac,
gia
thanh
re. ZnO
thiromg
dugc
dung lam vat lieu cho cac
Hnh
kien quang
dien
tir.
ZnO c6 hieu suat
lucmg
tu phat quang c6 the dat tai gan
100%,
ma
ra trien vong trong viec che tao laser ZnO nhiet do
phong.
Mang mong ZnO
CO
do dan dien va do truyen qua quang hoc cao trong mien anh sang nhin thay
dugc
umg

dung lam dien
cue
trong suot cho pin mat trai chat
lirgmg
cao va gia
thanh ha. Cac mang ZnO dan dien trong suot con
dirge su
dung trong cac man
T
t ' /
hinh tinh the long, cac
cOra
so dien
tir,
cac thiet
bj
quang hoc uon dugc, cac
gu^ong
phan xa nhiet de
phii
va kho phu, tham chi hot ZnO con c6 ung dung
trong che tao kem chong nang.
Dae
biet,
trong
nhiJng
nam gan day, cac nha
khoa hoc tren the
gicri
dang tap trung nghien curu vat lieu ZnO cau

true
nano
vai nhieu hy vgng trong viec che tao mot the he
linh
kien
mai
c6 nhieu tinh
chat
UTJ
viet so vai cac mau khoi.
2.
Noi dung nghien
ciifu:
De
thuc
hien
dirge
muc tieu neu
d
tren,
d^
tai da giai quyet dugc eac
vSih
de sau:
+
Che tao mang ZnO c6 chat
liigng
cao bang
phuofng
phap phun xa r.f.

magnetron tren thiet
bj
Univex - 450 cua hang Leybold.
-
Lam chu dugc thiet bi Univex - 450 cua hang Leybold.
- Che tao bia ZnO va ZnO pha tap
tiT
bot ZnO va
b6t In203
cua
hang Merck bang
phuofng
phap gdm tmyen thong tren cac thiet bi cua
du
an
OPEC.
+
Che tao mang
In+Al
bang
phuong
phap boc bay
nhi^t
trong chan
khong.
3.
Cac ket qua dat
dirac:
+ Dua
cac thiet bi che tao mang mong bang phun xa

catdt
Univex-450
va boc bay nhiet trong chan khong
Univex-300
vao boat
d6ng
c6 hieu qua.
+
Che tao thanh cong cac
loai
bia ZnO va ZnO pha tap bang phuofng
phap gom
truy6n
thong.
-h Tim
dugc che do cong nghe de che tao mang ZnO va mang ZnO pha
tap In tren de p-Si va de thuy tinh bang
phucDmg
phap phun xa r.f. magnetron
tren thiet bi Univex-450.
+
Che tao mang quang tra ZnO nhay a vung UV.
+ Che tao thanh cong pin mat trai n-ZnO:
In-p-Si
de lam cam bien nhay
quang.
I
If
f
+ iJng

dung lap chuyen tiep p-n lam cam bien dong ma tu dgng den
duong.
+
Cong tac nghien curu:
1/
Preparation
ofn-ZnOAn/p-Si heteroj
unction by r.f magnetron
sputtering. Nguyen Viet Tuyen, Ta Dinh Canh, Pham Van Ben, Bach
Van Sy, Nguyen Xuan Nghia, Tran Thi Quynh Hoa and Nguyen Ngoc
Long Proceedings of
the
eleventh Vietnam-German seminar on Physics
and Egineering, Nha trang 2008 (In the press)
2/
Photoconductive
UV detectors
based
on ZnOfdms
prepared by RF
magnetron sputtering
method,
Nguyen Viet Tuyen, Ta Dinh Canh and
Nguyen Ngoc Long. Comm. In Physics, 2008 (in the press)
-h
Cong tac dao tao :
*
Da
hudng
dan 2 khoa

luan
tot nghiep
1/
Nguyen Si
Hieu,
''Che
tao va khao sat mang ZnO
d6'
thuy tinh
bang hoc bay nhiet kem axetat trong chan khong" Ha Ngi - 6/200L
2/
Nguyen
Hong Viet,
"Che
tao va khao sat mang ZnO pha tap
Al
tren de thuy tinh bang phuong phap
phiin
xa R. F
magnetron",
Ha
Ngi-
6/2002.
* Da
hudng
dan
1
luan van cao hoc:
r
1/

Bach Van Sy,
''Che
tao va khao sat mang ZnO,
ZnO
pha tap lam
sensa
nhay quang vung
UVva
VIS'''
- Ha Noi, 12/2008.
* Dang
hirdng
dan
1
nghien curu sinh trong hu6ng nghien curu nay.
4.
Tinh hinh su dung kinh
phi:
Tong kinh phi
thirc
chi: 20.000.000 d6ng
(mudi
lam trieu dong chan),
Trong do cac khoan da chi:
Thanh loan dich vu cong
c6ng
: 600.000 d (tien dien)
Thue mu6n :
8.500.000
d

Chi
phi
nghiep vu chuyen mon : 10.300.000 d
Chi
phi
khac (QLCS): 600.000 d
Da
thSng
qua churng
tijr
tai phong tai
vii.
Xac
nhan ciia
ban
chii
nhiem Khoa
(Ky va ghi ro ho ten)
Chii tri di
tM
(Ky va ghi ro ho ttn)
PGS.TS.Nguyen
The Binh PGS.TS.Ta
Dinh Onh
Xac nhan
ciia Trucmg
DHKHTN
»M6
HI?U
TRl/ONG

o
l;^-:
DAI
I
Brief of the Report
1.
The title of the project
Fabrication, investigation the properties of n-p heterojuction based
on ZnO thin films and their ability of applications.
The code number: QT - 08 - 16.
2.
Main responsible person: assoc.
prof.
Dr Ta Dinh Canh.
3.
Main implementation numbers:
Bachelor Nguyen Viet Tuyen
4.
The objects.
The
n-ZnO:In/p-Si
heterojunction solar cells were made by
magnetron sputtering. The wavelength dependent properties of the
photoresponse for the heterojunction were investigated in detail by
studying the effect of light illumination on current - voltage
(I-V)
characteristic, photocurrent spectra at room temperature. From the
photocurrent spectra, it was observed that the visible photons are
absorbed in the p-Si layer and under reverse bias conditions, while
ultraviolet (UV) photons are absorbed in the depleted

n-ZnO:In
under
reverse bias conditions. These
resuhs
indicated that
ZnO:In
films
prepared by the r.f. magnetron sputtering are good enough to be used
in photoelectrical devices.
5.
The content of research.
The p-type Si (100) wafers (7-25
Qcm)
were used as substrates for the
ZnO:In/Si
heterojunction. Si (100) wafers were cut into pieces of
lilcm.
Prior to the deposition, the wafers were dipped into buffered oxide etchant
(HF:H20
= 1:7) for
1
minute to remove native oxide. Then the samples were
ultrasonically cleaned with boiling acetone, ethanol, and de-ionized water for
10 min. ZnO:In films were deposited with an r.f magnetron sputtering
system using a
ZnOiIn
(2%) target with diameter of 7.5 cm and 0.5 cm thick.
The sputtering parameters were optimized at a substrate temperature of 150
''C,
r.f. power of 250 W and sputtering Ar pressure of

5.8110'^
Torr. After the
ZnO:In
film was deposited, for measuring the electrical properties, an
hi
ohmic contact (0.5 mm diameter) was made onto the
ZnO:In
films being
used as a top electrode and an
In-i-Al
ohmic contact was made onto the p-Si
substrate being used as a bottom electrode.
The resistivity of the
ZnO:In
film was measured with a four-point
probe system. The dark
current-voltage (LV)
measurements were done
keeping the sample in the dark for several hours by using a Keithley
multimeter (Model 2400).
6. Results:
1/
Preparation
ofn-ZnO:In/p-Si heterojunction
by r.f magnetron
sputtering. Nguyen Viet Tuyen, Ta Dinh Canh, Pham Van Ben, Bach
Van Sy, Nguyen Xuan Nghia, Tran Thi Quynh
Hoa
and Nguyen Ngoc
Long Proceedings of

the
eleventh Vietnam-German seminar on Physics
and Egineering, Nha trang 2008 (In the press).
2/
Photoconductive
UV detectors
based
on ZnOfdms
prepared by RF
magnetron sputtering
method.
Nguyen Viet Tuyen, Ta Dinh Canh and
Nguyen Ngoc Long. Comm. In Physics, 2008 (in the press)
7.Conclusion
* Obtaining the aims of the project.
* Training 2 graduate students,
1
master student.
MUC LVC
Trang
MQ
DAU 1
Chuang
1:
TONG
QUAN VE
VAT LY BAN DAN 3
1.1 Co so phan loai vat lieu 3
1.2
Phan loai vat lieu ban dan 5

1.2.1 Ban dan thuan 5
1.2.2 Ban dan loai p 7
1.2.3 Ban
din
loai n 8
1.3
CSu true
tinh
thi
ZnO
11
1.3.1
Cau
true
tinh the ZnO
luc
giac
11
1.3.2
cau true
tinh
thi
ZnO don gian
kidu NaCl
12
1.3.3
Cau
true
mang lap phuong gia kem
(zine

blend)
13
1.4
Cau tnic
viing
nang
lugng
cua ZnO
14
1.4.1
Cau tnic vung nang lugng cua ZnO dang luc giac 14
1.4.2
Cau
true
vung nang lugng cua ZnO dang gia kem
15
1.4.3
Cau tnic vung nang lugng cua ZnO dang lap phuong dan gian
ki6u
NaCl 16
1.5
Tinh chat dien
ciia
ZnO 17
1.5.1 Dich chuyen trong dien trucmg thap
17
1.5.2 Dich chuyen trong dien trucmg cao 18
1.5.3
Tinh chat dien cua ZnO pha tap 19
1.5.3.1

Tinh chat dien
ciia
ZnO
pha
tap loai n 19
1.5.3.2
Tinh chat dien cua ZnO pha tap loai p 20
1.6
Tinh
chat quang cua vat lieu ban dan 23
1.6.1
Cac dac trung quang 23
1.6.2
Cac
CO chi hdp
thu anh
sdng
24
1.7
Tinh chat quang cua ZnO 27
1.7.1
Cac exciton tu do 27
1.7.2
Cac exciton lien ket 28
1.8
Cac tiep
xiic
trong ban
din
30

1.8.1
Tilp
xuc p-n dong
thi
30
1.8.2
Tiep xuc p-n di the
31
1.8.3 Tiep xuc Ohmic 33
Chuang
2:
CAC PHUONG PHAP
THI/C
NGHIEM 36
2.1 Cac ky thuat phun xa 36
2.1.1
Phiin
xa nguon mot chieu
37
2.1.2
Phiin
xa nguon xoay chieu 39
2.1.3
Phiin xa magnetron 40
2.2 Nghien curu cau tnic bang phuang phap
nhilu
xa tia X 41
2.3 Quan sat hinh thai be mat bang kinh
hiln
vi dien tu quet (SEM) 43

2.4 Do dien tra suat 43
Chuang 3: KET QUA,BIEN LUAN, VA
iTNG
DUNG 45
3.1 Che tao va khao sat lap chuyen tiep
n-ZnO:In/p-Si
45
3.1.1 Khao sat cau tnic 45
3.1.2
Khao sat tinh chat quang 46
3.1.3 Khao sat tinh
chSt
dien 48
3.2 Sur dung lop
chuyin
tiep
n-ZnO:In/p-Si
lam thiet bi dong ngat tu dong he
thong chieu sang den duong 50
3.2.1
So ddkhdi
50
3.2.2 So
d6
chi
ti8t
51
KET LUAN 53
TAI LIEU THAM KHAO 54
MOfDAU

Trong cac hgp chat ban
din,
ZnO la
chit
ban
din
c6 dg rgng
viing
cam
Ian
(-3,3eV
d
nhiet do phong), do ben
vvhig
va nhiet do nong chay cao, gia thanh re. ZnO
thuang dugc diing lam vat lieu cho cac linh kien quang dien tu. ZnO c6 hieu suat lugng
^
y
t
'
tu phat quang c6 the dat tai gan 100%, ma ra trien vgng trong viec che tao laser ZnO
nhiet do phong. Mang mong ZnO c6 do dan dien va do truyen qua quang hgc cao trong
mien anh sang nhin thay dugc ung dung lam dien
cue
trong suot cho pin mat trai chat
lugng cao va gia thanh ha. Cac mang ZnO dan dien trong suot con dugc su dung trong
cac man hinh tinh the long, cac cua so dien tu, cac thiet hi quang hgc uon dugc, cac
guang phan xa nhiet de
phii
va kho phu, tham chi bgt ZnO con c6 ung dung trong che

f r \
'
tao kem chong nang. Dac biet, trong
nhumg
nam gan day, cac nha khoa hgc tren the giai
dang tap trung nghien curu vat lieu ZnO cau tnic nano vai nhieu hy vgng trong viec che
tao mot the he linh kien mai c6 nhieu tinh chat uu viet so vai cac mau khoi.
CHl/QNG 1
TdNG QUAN
V£
VAT
LI$U
BAN
DAN
LI Cor
so*
phan loai vat
lifu:
Buc tranh ve cac vung nang lugng cua dien tu trong
trudng tuin
hoan cua tinh
thi
cho phep ta xac
djnh
dugc
chit rln
la
chit din
dien hay la
chit each

di?n,
can
cur vao
viec cac dien tu khong lap
dly
hay c6
lip dly
cac vung nang lugng.
DI
lam viec do
ngoai viec phai biet cac vung nang lugng ta con can
nhac lai
rang vi cac
di?n
tu tuan
theo thong ke Fermi - Dirac cho nen trong moi trang thai vat
ly
(dac trung bai ham
song va hinh chieu spin)
ciia
dien tu chi c6
thi
hoac la khong c6 hat nao, hoac la c6
mot hat; khong the c6 hai dien tu
ciing t6n
tai
d6ng
thai trong mot trang thai vat ly. Khi
trong mot trang thai vat ly da c6 mgt dien tu roi thi ta noi trang thai do da bi chiem
hoac da day; neu con c6 cac dien tu khac thi cac

di^n
tu do phai
chilm cac
trang thai
khac ( nguyen ly loai
trii
Pauli).
Khi c6 mot trang thai ma trong d6 khong ton
t^i
mgt
dien tu nao ca thi ta noi trang thai do la con trong;
di?n
tu
tir
mgt trang thai khac c6 the
nhay vao chiem trang thai con trong nay.
MHtIS
Conduction Band
Valtnce
Band
Semiconductors
Conduction Band
Eg
Insutaton
Eg
Val*nct
Band
Conduclon
Band
^Itnct

Band
Hinh 1.1: Cau
true
viing nang
lu(mg
cua
kirn
loai,
ban dan va chat
each di^n
Gia su
chit rln
c6 mgt vung nang lugng ma mgt
phin dS
dly,
mgt
phin
con
trdng.
C)
nhiet do
T ==
0 cac trang thai vdi nang lugng duai muc Fermi
Ep
da
dly
hit,
con cac
3
trang thai vai

nSng lugng
tren muc
Fenni thi
hoan toan
trdng.
Nhtog tr?ng thAi
trong
sat muc Fenni c6
nSng
iugrng khac rat it so vai
nSng
lugng
c4c tr^g
thii di
dfiy d
sit
muc nay. Do do chi can
tmyen
them cho
h? di§n
tu mgt rat be la cung c6 the
Ikm
cho
dif
n tu chuyen
doi
tu trang thai
dly
sang trang thai trong, nghia
1^

lam thay doi
ph&n
bo nang lugng.
C) nhi^t
do
T #
0 c6 them
di$n tir
vcri
ntog
lugng tren muc Fermi vi
nhung trang thai chua
dly
vai
nSng
lugng
dudi
muc Fermi,
s\r
thay doi him ph&n
b4
khi truyen nang lugng cho
hf
cang de dang han, du cho do la
n&ig
lugng
rit
b6.
Khi ta
dat chat

ran
nay trong
di?n
trucmg, dien
trudng
tac
dyng len cic di^n
tu,
truyen nftng
lugng cho cac
di^n
tu va lam cho dien tu chuyen tu cac trang thai day sang
tr^ng
thii
trong,
lam thay doi ham phan bd va dan den
s\r
xuat
hi^n
dong
di^n
cho du
di$n
trudng
yeu.Chal
tin nhu vay la chat dan dien.Vung
nSng
lugng trong chat dan
di§n
mi

m^t
phan da day va mot
phSn
con trong ggi la
viing
din.
Kim loai c6
clu
tnic viing
ndng
lugng va su phan bo dien tu trong vimg
din
nhu
da
trinh bay a tren, nen la
chit
din
dien.
Trai lai, neu pho
nSng
lugng
ciia chAt
rin c6 mgt vimg
cim
vai
mpt
be rgng
A£
du
lom,

ma tat ca cac trang thai duai viing nay
dSu
da
dAy,
cac kich thich
nhi?t se
khong
the truyen du nang lugng cho dien tir
d^
no
chuyen
tir mot trang thai duai viing
elm
len
mpt trang thai tren
vimg
cAm,
do do khong
iM
lam thay
d6i
ham phan
b6,
nghia
li
khong
th6
lam
xuk
hien dong dien.

Chit
tin c6 clu tnic va su phan
b6 di^n
tu nhu
v$y
la chat
each
di^n.
Vimg nang lugng duai viing
elm,
gdm cac trang thai
da
dly,
ggi li
\ung hoa tri. Cac dien tu
lip
dly viing hoa tri
gpi
la dien tu hoa
trj.
Viing
elm
cang
rpng thi tinh chat
each
dien cua
chit
rln cang
t6t.
6

nhiet do
T ?t
0 khong
cin
qua
Ian,
thi du nhu a nhiet dp phong, cac
d^g
chuyen dong nhiet trong
chit
rln c6
thd truySn
du
ning
lugng cho
di^n
tir
dl kich
thich
Chung tir viing hoa trj da day len vimg
nSng
lugng con trdng a phia tren viing
elm,
lim
cho \
iing
n^ng
lugng con trong nay c6 cac dien tu phan b6
gidng
nhu a trong vimg

din
cua chat dan
di?n.
Viing nang
lugng con tr6ng do a phia ben ngay sat vimg
elm
cung
duac
gpi
la viing dan. Theo cong thirc phan
b6
Femii,
n6ng
dp
di^n tij
trong viing
din
CO
dp
Ion
vao ca:
n^^
e-'"'
(1-1)
e^^
+ 1
nh6 Hon
nhigu
so
v6i ndng d$

di^
tur
trong kim
lo^i.
Khi
c5 nhfhig di$n
ti^
chuy^
tir
viing
hoa trj len vung
din,
vugt qua vung
elm
c6
b£ rOng rlt
b^,
thi trong vung
hoi
tri
xult hi^n nhihig
trang thai
tr6ng.
Vi trong viing hoi tri bay
gid
l^i
c6 cic
tr^ng thdi
trong vdi
nSng

lugng v6
ciing gin ning
lugng cic
tr^g
thai
dly
cho nen
dudi
tic
d\mg
cua mot dien truang khong can
Ion llm
cic
di§n tii
trong vung hoa tri ciing c6
thi
thay
doi
sir
phan bo va do do cung tham gia vao
s\r
xult
hi^n
dong
di^n.
So cic trang thii
trdng nay trong viing hoa tri
bing s6 di^n
tu trong
viing

din.
Nhi^t dO
cang ting thi s6
nay cang tang.
Cac chat each dien ma viing cam c6 be rgng
A£
rat be tra nen
din
dien
6 nhi$t
dp
T
#0
khong qua
Ion
va dugc gpi la chat ban
din.
Cic chat ban dan c6
nhihig
tinh
chit
rat dac
bi^t,
lam ca so khoa hpc cho
s\r
ung
dyng
cic chat do trong ky thuat.
1.2
Phan

loai v|t
lifu
bin din
1.2.1
Bin
dan thuan
e
«
e
'
«
i
#
s
#
.
«a
«• «•
'
# S # I
#
e
ee
«•
••
'
#
S
'#
S # e

e e e
Hinh
1.2:
Lien
ket trong
ban
dan
thuan
Nhutig chit
ban
din
dan
chit
nhu Ge, Si hay hgp
chit
nhu GaAs,
InSb,
CdS thuln
khiSt
ve mat hoi hpc, khong
Ian
tap
chit,
khong lech hgp thuc, khong c6
cac sai hang clu tnic tich
di^n,
dugc gpi la cac
chit
ban din
thuin,

bin
din
rieng va
cung con gpi la ban dan loai I.
Vai loai vat lieu nay khi
6 nhi^t
dp OK, vimg
din
hoan toan trong, khong c6
di^n
tir
din.
Khi nhiet dp tang len, dien tu a vimg hoi tri c6
thfi
thu dugc mpt
ning
lugng
cIn thiSt
de vugt qua viing cam va nhiy len viing din,
dfi
l^i
a
viing hoa tri
"iP^
™^
khuy^t
dien tu.
K6t
qua la
a

vimg
din
xult
hi$n
cic
di§n
tu
din
va viing hoa tri
xufit
hien
mire
trdng vai ndng
dO
nhu nhau. Cic
di§n
tu
d viing din
va cac 16 trdng
d
viing
hoa trj
d6u
c6
th6
tham gia vao qui trinh dan
difn.
Trong cac ban
din lo^i
nay, muc

Fermi dugc xac dinh bdi cong thuc:
Vi£^^3
m^
(1.2)
2
4
m,
6
nhiet dp cao han, trir mpt sd truang hgp khi c6
s\r
chenh
l#ch I6n
ve khoi lugng
hieu dung nhu
a
InSb,
su
chuyin
dich cua muc Fermi theo
nhi^t
dp
li
khdng ding
kc.
Do do, ndng dp hat tai rieng cua ban
din thuIn
c6
thi
dugc
bilu diln

bdi bieu thirc:
n
=n^=iN,N,ycxp(-^)
(1.3)
Nhu vay trong ban dan
thuIn,
ndng dp hat tai dugc xac djnh bdi dp
rOng
viing
cam
Hg
va nhiet dp T
ciia
mlu.
Neu ta
dit
dien trudng vao
mlu sS
xuat
hi^n
dong
di§n.
1)6
la sy chuyen ddi c6 hudng cua dong thdi cac
di^n tix
d viing
din
va cac
Id
trSng d

\ iing hoa tri. Dp dan trong ban dan thuan dugc xac djnh bdi bieu thuc.
a
=
q(nn^
+ pjip)
(1.4)
Trong do n,
jin
tuang img la ndng dp va dp linh dpng cua
di?n
tir; p,
fip
tuang iimg
la nong dp va dp linh dpng cua
Id
trdng, q
=
e la
di?n
tich nguyen td. Nhu vay
djc dilm
dan dien rat quan trong cua chat ban dan thuan la su tham gia ddng thdi vdi sd lugng
nhu nhau
ciia
ca
di^n
tir tren viing
din lln l6
trdng trong viing hoa trj.
D$c

diem thu hai
la ndng dp cua chung phu thupc rat
m^mh
vao
nhi^t
dp.
Trong
linh
vuc
chi
tao vat
li^u
bin din,
dilu ki^n
cdng
ngh? th^rc tl
khdng cho
phep che tao dugc cac chat ban
din
hoin toan tinh
khilt
mi khdng bj
Ian
it nhilu
t?ip
chat. Mat khac, nhu da noi 6 tren, ban
din thuIn khifit
cd nhilu
d$c
tinh han

chi
khi
nang img
dyng thyc
tiln.
Vi vay ngudi
ta
chu dpng pha
th6m m$t
lugng
nguyfin
t6
khac
lo^i
vao chat bin
din
tinh khilt
di
d^t
dugc cic tinh
chit
mong mu6n. Trong
m^t
v^t
li?u
nhu
v$y,
tinh
din di^n
xult

hi^
chu
ylu
do
mOt lo^i
h^t
tii
mi
lo^
h^
tii niy
dugc^quy
djnh bdi
t^
chit pha vio, ngudi ta ggi cic vat
li^u
nhu
v^y
li cic bin
din
t9p
chit.
Tuy thugc ban
chit
cua vat
li^u
pha tap vao vat
lifu
bin
din

tinh khiet mi ngudi
ta
CO
the tao ra dugc
hoic
bin dan tap chat loai n
hoic
la ban dan tap chat loai p.
1.2.2
Bindlnlo^ip:
e e e
^
#
I •
S
# e
a e a
Hinh
1.3:
Lien ket trong ban dan
iogip
Gia sir
ring
c6 nguyen tir C vdi
n-1
di^n
tu vanh ngoai (hoi tri
n-1)
mi ham song
gidng nhu ham song cua n-1 trong sd n

dif
n tu vanh ngoai
ciia
nguyen tu
chit
A. Neu
ta thay mpt nguyen tu A bang mpt nguyen tu C thi n-1 dien tu vanh ngoai cua C chua
du
dk
thay tat ca n
di^n
tu vanh ngoai cua A vi con thieu mat mpt
di^n
tu, do dd trong
viing hoa tri c6 mpt trang thai trdng ngay ca khi T
=
0. Neu ta pha tap chat C vao
chit
ban
din
de cac nguyen tu C thay the mpt sd nguyen tu A, thi trong viing hoi tri xult
hien cac trang thai trdng, nghia la
s0
cd cac
l6
trdng, ngay ca d nhiet dp T = 0. Khi ta
tang nhiet dp T thi lai cd them mpt sd dien tu bi kich thich tir viing hoi trj len vimg
din,
lam cho trong viing
din

cd cac dien
tii,
trong viing hoa trj cd them
Id
trdng.
Hi^u
sd ndng dp Id trdng va ndng dp dien
tii
la mpt lugng khdng ddi va
blng
ndng dp tap
chat.Cac
l6
trdng la cac hat tai dien chinh.
Chit
ban
din
nay gpi la chat ban
din
loai p
(positive). Ndng dp
l6
trdng trong ban
din
loai p:
p = (N^N J cxpi-^)
(1.5)
2kgT
1.2.3 Ban dan loai n:
e e e

'
9
I
#
s
#
•
ee
«»
ae
«
t
I
•
s
•
e
ee ee
«e
'
t
I
#
I
#
e
e e e
Hinh
1.4:
lien kit trong ban dan

logi
n
Xet mpt
chit
ban
din
cd chua cac nguyen tu
ciia
mpt chat A nio dd. Gii sd
m8i
nguyen tir
/4
c6 n dien tir vanh ngoai ( hoi tri n ) la nhihig
di?n
td trd thanh m5i nguyin
tir
luu
dpng trong
chit
rln.
Tit
ca cac
difn
tu nay lap dly vung hoi trj khi
T =
0 vi
cung chi vira du de lap day viing hoa trj. Ta hay thay the mpt nguyen tu A trong tinh
th^
bang mpt nguyen tu
5

c6 n
+1 di?n
tu vanh ngoai (hoi tri n +1) ma neu
lly
di
mOt
di^n
tir vanh ngoai thi ion duong fl* con lai cd cau tnic
di^n
tu gidng nhu
nguySn
tdi^.
Khi do n dien tir vanh ngoai cua ion
B^
thay the n
di$n
tu vanh ngoii cua
nguygn txxA
bj lay di va ciing vdi cac
di^n
tir vanh ngoai cua tat ci nguyen tu A khic
lip
dly viing
hoa trj
khi
7=0.
Con mpt dien tu vanh ngoai nua bj thira ra cua nguyen tu B thi sao? Vi trong viing
hoa trj khdng con trang thai trdng nao
nQa
cho nen

di?n
tu nay chi cd the chilm
m^t
trang thai trong viing dan va trd thanh dien tir dan. Do dd
nlu
ta pha
t^p
chit B vio
chat ban dan A de cac nguyen tu B thay the mpt sd nguyen tu A, thi trong vung
din s€
CO
cac dien tir dan ngay ca d nhiet dp
r=
0, chat bin
din
trd thanh
din di^n
mi cic
h^t
tai
di^n
chinh la cac
di^n
tir.
6
nhiet dp
F
9^
0 vi cd them cic
di^n

tir bj kich thich tir
vimg hoa tri len viing
din
cho nen ndng dp
di?n
tu trong viing
din
ting len, ngoii ra
l^i
CO
them cac
Id
trdng. Hieu so ndng
di?n ni
va ndng dp
I6
trdng la mgt lugng khdng
dli
va bang ndng dp
t^p
chat. Chat ban dan nay gpi la bin
din lo^i
n (negative).
Rd rang la d viing
nhi?t
dp
thip,
khi ma
kBT«ED ho$c
kBT«E»,

qui trinh
chuyen
ddi
h^t
tii tir viing hoa
tq
len viing
din
li khdng ding
kl.
H^t
tii
di^
dugc
t90
8
thanh chu
ylu
li do
kit
qui cua qui trinh ion hoi cac nguyen tu tap
chit.
Do
v$y,
ndng
do can blng cua
h^t
tii trong trudng hgp nay phu thugc vao ndng dg
t^p
chit

Nd,
N
Cu
thi
la:
Ndng
do di^n
td trong ban
din
loai n:
/i = (A^,A^^)^exp( f^)
(1.6)
Do cic mire
ning
lugng tap chat nhd han nhieu so vdi
ning
lugng vung cam nen
su phu thugc
ciia
ndng dg hat tai vao nhiet do trong ban
din
tap chat yeu han nhilu so
vdi trudng hgp ban
din
rieng.
Theo chieu tang
ciia
nhiet dg, sd lugng nguyen tu tap chat bj idn hoa ting din. Do
lugng tap chat pha vao ban dan la
hihi

han nen se den
liic
toan bg cac nguyen
tiir
t^p
chat bi idn hoa het. Trong trudng hgp nay, ndng dg hat tai blng ndng dg nguyen
td
t^p
chat va trd nen khdng thay ddi theo nhiet dg,
tire
la:
n = Nd
va
p = Na
Nhiet dp
Ts,
ma tai do xay ra
hi?n
tugng nay,
ph\i
thugc vao muc
ning
lugng
t^p
chat va ndng dp tap chat.
Cy
the la :
Ts =
^''{j,
(1.7)

Khi
nhi?t
dp
tilp
tuc tang, ndng dp hat tai dugc tao thanh bdi qua trinh chuyen
ddi dien tu viing hoa trj len vimg
din
cung tang len trong khi toan bd cic nguyen tu
t^p
chit
da bj idn hoa het. Ban dan tap chat chuyen thanh ban dan thuan vdi ndng dp hat tai
la n, va
p
. Nhiet dp chuyen tiep
Tj
cd
thi
xac dinh bdi bieu thirc:
(1.8)
'
kM^c^ylKia,)
r)
Thong thudng nguyen tir tap chat dugc
lua
chpn sao cho d nhiet dp lam viec,
nang lugng nhiet tai nhiet dp dd du
Idn
de ion hoa hau nhu hoan toan cac nguyen tu
donor hoac acceptor trong chat ban dan. Nhu vay, dong
di^n

trong cac ban
din
tap
chit
it bj thay ddi theo nhiet dp nhu trong trudng hgp cac chat ban
din
thuan khiet.
D$c dilm din difn
chu ylu blng
m$t lo^i h9t
tii
19!
ft bj
phy thu^c
vio
nhi^
t
lam cho cic ban
din
t^p
chit trd thinh mpt
vit li^u
qu^^
trong
lihh
v\rc
chi
t^o
ciclin
kien dien tu nhu diode, transistor

hoic
cic
m^ch
t6 hgp Dd chinh li
co
sd cho
mi
cudc
each
mang trong
ITnh
vuc
ky
thuat
vacdng ngh§ di^n
tiir cung nhu cdng
ngh
thdng tin.
Khi nghien cuu clu tnic dien tu ciia cac chat
din di^n
va cic chat cich
di$
chung ta da
thiy ring
trong
chit
bin
din,
la
chit

cich
di^n
ma viing
elm
cd
bl rOng A
rlt be, d nhiet dp
Ti^O
mpt sd dien tu bi kich thich tir viing hoi trj len vung
din
va
tr
thanh dien tu dan, de lai trong viing hoa tri nhumg
I6
trdng ciing li cic
h^t
tii
di^
Ndng dp cac hat tai phy thugc
nhi^t
dg T theo cdng thuc . Cic chat bin dan dd dug
gpi la cac chat ban
din
thuan, cd tinh chat cich
di^n
khi dugc
giO"
d
nhi^t
dp

r=
0.
Tom lai, neu ta pha tap
dl
thay mgt sd nguyen tu mgt
lo^i
nio dd
ciia chit
bi
dan bang
nhOmg
nguyen tiir cd cau
t^o
tuang ty nhung vanh ngoii cd
thfim
m^t
di^n
ti
thi ta
sS
dugc mgt chat ban
din
loai n mi
di?n
tir la
h^t
tii chinh, ndng dg
di§n
td
W

han ndng dp
Id
trdng. Tap chat
lo?ii
nay gpi la chat
hifin di^n
tu (donor).
M$t
khic,
n^
ta pha tap de thay mpt sd nguyen tir mpt
loai
nio dd
ciia
chat ban
din
blng
nhthi
nguyen tu c6 cau tao tuang ty nhung vanh ngoai cd bdt di mpt
di^n
tu, thi ta
s€
du^
mpt chat ban dan loai p ma Id trdng lai la
h^t
tai chinh , ndng dp
Id
trdng
Idn hem nil
do dien tir. Tap chat loai nay gpi la tap chat nhan

di?n
tu (acceptor).
Chu y
ring
khi ta pha tap nguyen tu B vao
chit
bin dan de thay
thi
cho
nguyin
ti
A thi mpt dien tir vanh ngoai cua B bj du ra va trd thanh
di?n
tu
din,
cho nen
thyc SU
chi
CO
ion duong
B*
thay the nguyen
ta
A mi thdi. Tai nut chua nguyen tu B bay gid
cc
them mpt dien tich
+e
so vdi khi chua
thay.Trong
trudng coulomb ciia

di^n
tich duan|
nay cac dien
lir
dan c6 cac trang thai lien kiet gidng nhu nguyen tu hydro, vdi
ninj
lugng am so vdi nang lugng tdi thieu cua dien tir ty do trong viing
din.
Mire
nan|
lugng gian doan nay nam trong
voing
cam va gpi la muc
ciia
tap
chit
hiln
di^n tii
(min
donor ). Ngugc lai, so vdi nguyen ni A thi nguyen tu C con
thilu
mpt
di?n
tu, cho
nft
khi
C thay vao cho
ciia
A thi nguyen tir C con
bit

them mpt
di?n
tir vimg hoa trj vi tri
thanh mot ion am C thay the A. Tai nut chira C bay gid cd them mpt
difn
tich
-c «
10
vdi khi chua thay. Trong trudng Coulomb cua
di^n
tich -e niy cic
Id
trdng mang
di^
duong
cQng
cd cic
trsmg
thii lien kit, vdi
ning
lugng am so vdi
ning
lugng tdi thilu
cua
Id
trdng
t\r
do.Vi ning lugng cua
Id
trdng cd

diu
ngugc lai so vdi ning lugng cua
trang
thai
trdng, tinh tir
mure
Fermi
nim
trong vung cam, cho nen neu quy
vi
trang thii
trdng ciia
di^n
tu thi nguyen tu C tao ra them cac muc ning lugng gian doan cd gii tri
duong so vdi cue dai viing hoa tri, nghTa la cung
nlm
trong viing cam. Cac muc niy
gpi la cic muc ciia tap chat nhan dien tu (muc acceptor).
1.3 Cau
true
tinh the ZnO.
Ve mat ly thuyet, ZnO khdng phii la mpt vat
li?u
mdi dugc khim phi. Cic nghiin
cim tren ZnO da dugc thyc
hi?n
lien tyc trong nhieu thap ky, ve
mit
tinh chat cua nd, di
cd cac bai bio tir

nam
1935, tham chi sdm han. Vi dy, hang sd mang
ciia
ZnO
dS
dugc
khao sat tir nhieu nam trudc.
Nhung
nghien cuu da chi ra
ring
ZnO tdn tai trong ba loai
cau tnic ca ban: cau tnic lap phuang gia
kSm
kieu sphalerite
(B2),
cau tnic lye giic kieu
wurtzite (B4) va cau tnic lap phuang don gian kieu NaCl
(Bi).
Tinh the ZnO la chat diin
mdi,
d dieu kien binh thudng bin
vihig
vdi cau tnic luc giic wurtzite. Khi ip suit thuy
tTnh cao ZnO cd cau tnic lap phuang dan giin kiiu NaCl va d
nhi^t
dp cao ZnO cd clu
tnic gia kem khi nudi
cly
tren de clu tnic lap phuang.
1.3.1. Cau true mang

lye
giac wurtzite.
Cau tnic luc giac wurtzite la cau tnic dn dinh va ben vimg
ciia
ZnO d dieu
ki^n
nhiet dp phong va ip suat khi quyin va thupc ve nhdm khdng gian
P63mc hoic
CV-
Cd thi hinh dung mang wurtzite gdm hai phan mang lye giac xep chat (hpc)
Idng
vao
nhau va dugc djch di mpt khoang bang u = 3/8 chiiu cao (trudng hgp cau tnic ly
tudng),
mdi phan mang nay gdm 4 nguyin
tii
cung loai trong mpt d mang dan vi. Mpi
nguyen tir nhdm II dugc bao quanh bdi 4 nguyin tu nhdm VI hoac ngugc lai. Trong
thyc ti, hai phan mang nay
Idng
vdi nhau khdng
diing
vdi gia trj 3/8 chiiu cao ma
tiiy
theo timg loai cation, gia tri djch
chuyin
nay se khac nhau. Mpt trong nhung tinh
chit
dac trung cua phan mang luc giac xip chat la gia tri ty sd
giira

cac hang sd mang c va a.
Trudng hgp ly tudng thi ty sd c/a =
>/3/8
= 1,633. Tren thyc te, cac gia trj cua ty sd
II
c/a ciia hgp chat
A"B^'
diu nhd han 1,633. Diiu niy churng td cic
m$t
khdng hoin
toan xip chat.
Tinh thi luc giic ZnO khdng cd tam ddi
xiing,
do dd trong
m^g
ton
t^i
tryc
phin
cue
song song vdi hudng
[0001].
Liin kit
ciia
m^g
ZnO vira li
liin
kit ion
vvra
li

liin
kit cdng hoa tri, li loai liin kit pha trpn bao gdm 67% liin kit ion va 33% liin kit
cdng hoa tri. Dac diim quan trpng
ciia
liin kit cpng hoa
trj
li tinh
dj
hudng vi tinh bio
hoa vi mdi nguyin tu chi cd the cd nhiiu nhat mpt sd lien kit
cOng
hda
trj
nio dd.
O
Hinh
1.5
Cau
true
mang tinh the luc giac kieu wurtzite cua ZnO.
1.3.2. Ciu triic
m^ng
lap
phuong don
giin kieu NaCl
Nhom ddi ximg khdng gian cua cau tnic nay la Fm3m. 6
m^g
co sd
ciia
clu true

lap phuang dan giin kieu NaCl co the dugc xem nhu gdm hai phin
m^g
%
phuong tim
m^t
cua cation (Zn) va anion (O) Idng vao nhau,
Uong dd
phin
m^ng
anion (O) djch di
mpt doan blng
a/2,
vdi a la canh hinh
l^p
phuang. Moi d ca sd gom bdn phin
tu
ZnO
(hinh
1.6).
Sd
Ian
can gan nhat cua cation va
anion
diu blng 6.
^Zn
Hinh
1.6
Cdu true mang tinh
thi
Igpphuang

dm
gidn
kiiu
NaCl ciia
ZnO.
12
COng gidng nhu
m$t
sd
chit
bin
din
A°B^,
ZnO clu
true kiiu
wurtzite cd
thi biln
ddi sang hinh thii clu
true
gii
bin
1|^
phuang don giin
kiiu
NaCl d ip
suit thdy
fihh
dii
cao
vi ngugc

l^i
tiiy
theo
nhi^
dg vi ip
suit.
Diiu niy li do sy giim
kich
thudc
m^ng
tinh
thi
gay nin tuang tic Coulomb
gii^a
cic ion. Sy can blng pha dugc thiit
l|p
d ip
suit
khoang
lOGpa.
Theo tinh toan, su thay ddi thi tich ciia hai trang thii nay vao cd 17%
va
hlng
sd mang trong cau tnic nay a = 4,27A.
Gin
day, cac nghiin curu churng minh
sy chuyin pha clu tnic da quan sat
thIy
ZnO clu tnic lye giic wurtzite trii qua
mOt

sy
bien ddi cau tnic vdi ip
suit
chuyin pha p =
lOGPa
va hoan thinh d khoing
15GPa.
1.3.3. Cau true mang lap
phvorng
gia kem
Day cung la mpt trang thai cau tnic gia bin cua ZnO nhung xuat hien d nhiet dp cao.
Nhdm ddi xumg khdng gian ciia cau tnic nay la
T^
- F?
3m va gdm hai phan mang lap
phuang tam dien (fee) xuyin vao nhau 1/4 dudng cheo cua d mang. Mdi d co sd (hinh 1.3)
chira bdn phan tu ZnO vdi cac tpa dp
ciia
4 nguyin tu Zn la:
(0,0,0),
(0, 1/2, 1/2),
(1/2,0,
1/2), (1/2, 1/2, 0) va tpa dp ciia 4 nguyin tu O la: (1/4, 1/4, 1/4), (1/4, 3/4, 3/4), (3/4, 1/4,
3/4),
(3/4,3/4,
1/4). Trong cau tnic nay, mpt nguyin td bit ky dugc bao bdi bdn nguyin tu
khac loai. Mdi nguyen tu O dugc bao quanh bdi bdn nguyin tu Zn
nim
d dinh ciia tu
di?n

cd khoang
each a
>^
/2,
vdi a la thdng sd
ciia
mang lap phuang. Mdi nguyin tu Zn (O) con
dugc bao bdi
12
nguyin tu ciing loai,
chiing
la
Ian
can bac hai, nlm tai khoang cich
af-Jl.
Do su phdi vj theo kiiu tir dien
ciia
cau tnic wurtzite va lap phuang gia kem, 4
Ian
can
gin
nhit
va
12
Ian can bac hai cd ciing mpt khoing
each
liin kit trong hai trudng hgp.
Hinh
1.7.
Cdu true

mong
lap
phuang
gid
kem cua tinh the ZnO.
13
1.4. Cau
triic
viing ning
Ivgng
cua ZnO
1.4.1. Cau
true viing
ning
Ivgng ciia
ZnO dang
lye
giic wurtzite
Tat ca cac hgp chat
A"B^
diu cd vimg cam thing vi dp rgng vimg elm giim khi
nguyen tu lugng ting. Mang tinh thi ZnO dang wurtzite clu
t^o
tir hai
m^ng
lyc
giic
ling
vao nhau, mgt mang chua anion va mang con lai chira cation. Cic
victo tjnh

tiln co sd ddi
vdi mang luc giac wurtzite la:
- 1
a,
=-a(l,-V3,0);a2
=-a(l,V3,0);
a,
=c(0,0,l)
(1.9)
la
biet mdi lien
h?
giua
vecto
tjnh tiin co sd cua
m^g
thyc vi
m?mgdio:
ajCa^xaj) a2(a3xa,)
a^{a^xa^)
(1.10)
Vi vay mang dao ciing cd cau tnic lyc giic vdi cac
victo
tjnh tiin co sd li:
b;
=
2na''(l,-V3,0);
b^
=
27ia-'(l,V3,0);

b^
= 27ic-'(0,0,1)
(1.11)
Cau tnic luc giac ciia ZnO thugc nhdm ddi xung khdng gian
CV
(P63mc).
Vimg
Brillouin thir nhat la mpt khdi bat
di?n
dugc biiu dien trin hinh
1.8.
Hinh
1.8
Vimg Brillouin
ddi vai mgng tinh thi wurtzite.
14
Hinh
1.9 Cdu
true
vung ndng
lir^mg
cm mgng tinh the wurtzite.
Bang phuang phap nhiiu loan cd thi tinh dugc viing nang lugng cua mang lyc
giic tir viing ning lugng ciia mang lap phuang. So dd viing din (CB) va viing hda trj
(VB) ciia hgp chat nhdm
A"B^'
vdi
m^g
tinh the lyc giic dugc cho trin
huih

1.5. So
vdi so dd viing ciia mang lap phuang ta thay
ring,
muc
Fg
(J = 3/2) vi
F?
(J = 1/2)
ciia
viing hda trj do inh hudng
ciia
nhieu
lo^
trudng tinh
thi,
hi tich thinh 3 phan vung
r9(A),
r7(B)
va
r7(C)
trong mang lyc giac.
1.4.2.
Cau
true
viing ning
Ivgng
cua ZnO dang
l^p
phvong
gii kim (zinc blende)

Hinh
1.10.
Vung
Brillouin cua mgng tinh the
lap
phuang gid kem
15
Mang lap phuang gia kim cd cau tnic ddi
xixng
tjnh tiin cua
m^ng
1^
phudj
tam mat vdi cac vecto tinh tiin co sd li:
a,
=^a(U,0);
a,
=^a(l,0,l);
a,
=^a(0,U)
d.
^ ^
Mang dao dang lap phuang tam khdi cd cic vecto tinh tiin ca sd la:
-I
b,
=2Ka-'(l,l,-l);
b,
=27ia-'(l,-l,l);
bj =2nc-(-1,1,1)
(1.13

(1.13
Vimg Brillouin la mpt khdi bat
di?n
cyt.
1.4.3. Cau
true
viing nang lugng cua ZnO
d^ng
lap
phu-ong dom
giin
kiiu
NaCl
Cac vecto tinh tiin co sd
ciia
mang lap phuang don giin kiiu NaCl giong
nh
trong mang lap phuang gia kim.
a,
=ia(l,l,0);a2
=^a(l,0,l);a3
=ia(0,l,l)
(l.H
Vi ly do do viing Brillouin cua
lo^i
mang nay
h^t
nhu trudng hgp
m^g
l|p

phuang gi
kim.
So dd viing nang lugng
ciia
ZnO vdi cau tnic tinh
thi
d^ng
lyc giic
kiiu wurtziti
lap phuang gia kim (zinc blende) va lap phuong don giin
d^g
NaCl dugc cho
ti<
hinh 1.11.
15
to
5
S
I"
?
-5
III
V
-15
-20
• -^ —"^^
•
^^^^>r:^\
B4
ZaO

(a)'-'
•
M
Hinh
l.lLSado
vi^ng
ndng
luang ciia
tinh thi ZnO
16
1.5. Tinh chit
difn cila
ZnO
Li mgt
\^X li^u
vung
elm
thing rgng, ZnO thu hut dugc nhieu sy chii y ddi vdi cic
img dung
di^n
tiir vi quang
di^n
tu.
Nhung
thuan
Igi
liin quan
din
vimg elm thing bao
gdm:

hi#u di^n
thi dinh
thiing
Idn,
khi ning duy tri trudng dien cao Sy djch chuyin
electron trong vat
lieu
bin
din
cd thi dugc khao sit ddi vdi cic trudng
di^
thap vi cao.
-
Ddi vdi trudng dien du thap, ning lugng cua cac electron thu dugc tir trudng
ngoai la nhd khi so sinh vdi ning lugng
nhi^t
cua chiing, vi vi thi phd ning lugng
ciia cac electron khdng bj thay doi bdi trudng ngoai nhd do. Khi dd tdc dp tin
x^
xac dinh cua cac electron linh dpng phy thupc vao ham phan bd
ciia
cac electron,
dp linh dpng
ciia
electron ddc lap vdi trudng ngoai va dinh
luat
Ohm dugc quan
sat thay.
-
Khi trudng ngoii ting tdi diim ma ning lugng cic electron thu dugc tir trudng

ngoai khdng con la khdng dang ki so vdi nang lugng
nhi^t
ciia chiing
nC^a,
ham
phan bd electron thay doi dang ke tir cac gii tri can blng
ciia
chiing. Cic
difn
tu
trd thanh
difn
tu ndng, dugc die trung bdi mpt nhiet dp
Idn
han
nhi^t
dp mang.
Khi dd van tdc keo theo
ciia
cac dien tu
Idn
han cic gii tri d trang thii dn dinh ciia
nd.
1.5.1. Djch chuyen trong
di^n
trvdng thap
Hieu irng Hall la ky thuat dugc su dung rpng rai di do cac tinh chat dich chuyen va
danh gia chat lugng
ciia
cac

Idp
epitaxy. Ddi vdi vat lieu ban dan, nd tiet
Id
ndng dp hat
tai,
loai hat tai va dp linh dpng
ciia
chiing. Cy thi han, sd
li^u
thyc
nghi^m
cua cic phip
do Hall trong dai nhiet dp
Idn
tir 4,2 - 300K cung dp
nhung
thdng tin dinh lugng vi dg
tinh khiit, cac sai hong mang, tinh ddng diu cua vat lieu, co chi tan xa Hi sd Hall vi
dien trd
suit
p dugc xic dinh bing thyc nghiim va sau dd liin hi vdi cac tham sd dien
qua (ddi vdi tinh dan loai n)
RH
=
rn/ne
va
JIH
=
^H^P
trong do n la ndng dp

di?n
tu ty
do,
|iH li
dp linh ddng Hall,
rH
li hi sd tin xa Hall ddc lap vdi cac ca chi tin xa ndi
riing. Khi cac hat tai chuyin dpng qua chat ban
din,
chung bat gap nhiiu co chi tin xa
diiu khiin dp linh ddng hat tai trong hi dien tu khac nhau.
17
OAi
HOC
QL"^,
J)1
/
?5
3