Title :
Influence of the selenium/metal flux ratio on the crystallinity of widegap Cu(In/sub 0.4/Ga/sub 0.6/)Se/sub 2/ thin films and devices
Author :
Umeno, Yuuki ; Nakada, Tokio
Author_Institution :
Dept. of Electr. Eng. & Electron., Aoyama Gakuin Univ., Kanagawa, Japan
Abstract :
The influence of the Se/metal flux ratio on the crystallinity of widegap Cu(In/sub 0.4/Ga/sub 0.6/)Se/sub 2/ thin films with bandgap energy of 1.4 eV as well as the device performance has been investigated. The Se/metal flux ratio during the 1st stage of the modified three-stage process was varied from 10 to 118. As the Se/metal flux ratio was increased to 51, large crystal grains of CIGS thin films were observed to grow and the cell efficiency improved. Moreover, the (204)/( 112) peak X-ray intensity ratio increased, whereas, almost no change in the RHEED pattern was observed. These results suggest that the bulk crystallinity of high gallium content CIGS shin films as well as cell performance can improved by the optimization of Se/metal flux ratio. However, cell performance was still low compared to ClGS cells with lower bandgap energy. Therefore, other factors may be causing the decrease in efficiency of devices with bandgap energies above 1.3 eV.
Keywords :
X-ray diffraction; copper compounds; crystallisation; energy gap; gallium compounds; grain size; indium compounds; reflection high energy electron diffraction; semiconductor thin films; solar cells; ternary semiconductors; wide band gap semiconductors; (204)/( 112) peak X-ray intensity ratio; 1.4 eV; Cu(In/sub 0.4/Ga/sub 0.6/)Se/sub 2/; RHEED pattern; Se/metal flux ratio; bandgap energy; cell efficiency; crystal grain; crystallinity; device performance; modified three-stage process; thin film;
Conference_Titel :
Photovoltaic Energy Conversion, 2003. Proceedings of 3rd World Conference on
Conference_Location :
Osaka, Japan
Print_ISBN :
4-9901816-0-3
