Transcript Slide 1

XRD and SEM analysis
Name: Guogen Liu
Advisor: Prof. Chin
Co-advisor: Prof. Barat
Date: 07/24/2010
1. Glass and TCO
2. CdS
CdS is amorphous(XRD) and uneven in surface(SEM)
Both CdS layers (CBD or Sputtering)
are amorphous(XRD)
CdCl2 treatment didn’t result
in crystallization
There are lots of impurities on the
surface which result in uneven
From the XRD of one peak, we can make sure
CdS layer is amorphous
1. CdTe
Counts
Solar Cell-4_1
1600
CdTe before CdCl2
Pos. [°2Th.]
23.7248
26.5894
33.7510
37.7552
900
400
Height [cts]
1749.98
19.53
1.56
28.30
FWHM [°2Th.]
0.0984
0.2755
0.6298
0.1968
Grain size of the first peak
100
d-spacing [Å]
3.75039
3.35249
2.65572
2.38276
Rel. Int. [%]
100.00
1.12
0.09
1.62
g=81.5nm
0
30
40
50
60
70
Position [°2Theta] (Copper (Cu))
Counts
Solar Cell-5_2
900
g=90nm
CdTe after CdCl2
400
Pos. [°2Th.]
23.7457
26.4745
33.6422
37.7720
100
0
30
40
50
Position [°2Theta] (Copper (Cu))
60
70
Height [cts]
1287.22
19.54
1.93
32.08
FWHM [°2Th.]
0.0886
0.1968
0.4723
0.1574
d-spacing [Å]
3.74713
3.36678
2.66406
2.38174
Rel. Int. [%]
100.00
1.52
0.15
2.49
The CdTe grain size is very small, less than
100nm. After CdCl2 treatment, it increases a
little.
CdCl2 treatment increase CdTe grain size and crystallization
Thank you
Conclusion:
a, TCO surface should be clean completely
b, Add a thin resistivity buffer layer between TCO and CdS
c, CdS is not uniform and too much defect after
CdCl2 treatment
d, the grain size of CdTe is too small, close to amorphous
d, Oxygen is necessary in the growth of CdTe crystal
e, Vapor CdCl2 treatment is very important
f, It is better to increase CdTe deposition temperture
g, back contact and Cu doping can affect efficiency greatly
h, Pay more attention on the interface between each layer
i, try to convert thermal evaporation to CSS which is
much mature
j, try to do each step successfully first, then step by step