Optimization of CdTe solar cell performances using Ga-doped Mg
x
Zn
1-x
O buffer layers
Samah BOUDOUR
1,2*
, Idris BOUCHAMA
2
, Moufdi HADJAB
1,3
heraga 16014, Algiers / Thin Films
and Applications Unit (UDCMA), Setif-Algeria.
2
Electronic Department, Faculty of Technology, University of Msila, 28000, Msila - Algeria.
3
Applied Materials Laboratory, Research Center, University Djillali Liabes, 22000 Sidi Bel Abbes,
Algeria.
*Corresponding authot. Tel: +213(0)661242320; E-mail:
In this work, Ga-doped Mg
x
Zn
1−
x
O (GMZO) thin films were developed for application as
high resistance transparent (HRT) buffer layers (BL) in high efficiency CdTe thin films solar
cells. As the excellent electrical properties of Ga-doped Mg
x
Zn
1−
x
O varied according to the
gallium (Ga) and magnesium (Mg) concentrations, the use of GMZO thin films as both a
buffer layers and/or a transparent conducting oxides (TCO) becomes ever more flexible. We
have performed a computer simulation of (n+)-GMZO/n-GMZO/p-CdTe/MoTe
2
/Mo
proposed structure with AMPS-1D software in one dimension under AM 1.5 illumination.
The structure uses MoTe
2
layer as a pseudo contact between the CdTe absorber layer and the
Mo back contact. On the basis of a some experimental data, a high transparency and
conductive GMZO thin films can be obtained with Ga content around 0.5 at.%, and the high
resistive GMZO films with low Ga content. With varying the absorber thickness and the
carrier concentration, the effect of Mg concentration (
x
) on the performance of substrate
Ga(0.5 at.%)-doped Mg
x
Zn
1−
x
O (TCO layer)/Ga(0.05 at.%)-doped Mg
x
Zn
1−
x
O buffer layer/p-
CdTe absorber layer/MoTe
2
/Metal structure was investigated. As a result of calculation,
excellent performance can be obtained with high Mg concentration, the current density of
about 23 mA/cm
2
has been obtained for 3 μm-CdTe solar cell using
n
-type Ga(0.05 at.%)-
doped Mg
0.15
Zn
0.85
O buffer layer for 100 nm thick. It is also found that a conversion
efficiency of more than 17.1% AM 1.5 G could be expected for more than 3 μm absorber
thickness and acceptor concentration varying between 8 × 10
16
and 10
18
cm
–3
. From the
results obtained, we suggest the use of Ga-doped Mg
x
Zn
1−
x
O as a buffer and/or window
layers, to achieve high-efficiency CdTe solar cells with better photovoltaic parameters.
Key-words:
AMPS-1D, Ga-doped Mg
x
Zn
1−x
O, CdTe, Thin film solar cells.
PS2 31
-225-
