Title :
Induced defects in a-Si:H and a-Ge:H calculated by molecular orbital theory
Author :
Yoshida, Akira ; Matsuda, Yuji ; Nakanose, Koichi ; Ogawa, Hiroshi
Author_Institution :
Toyohashi Univ. of Technol., Japan
Abstract :
Gap states induced by weak bond and hydrogen movement in a-Si:H have been investigated on the basis of DV-Xα molecular orbital theory. Two energy levels appear near both sides of band edge, and shift to the gap center, while the weak bond is stretched and the bonded H atom is moved to the neighboring Si or Ge atoms. These additional states deep in the energy gap are due to the modification of bonding states, decreasing the electrical conductivity of a-Si:H. These facts give a possible explanation of light-induced degradation, when the weak bond and the movement of bonded H atoms are induced by prolonged exposure to intense light
Keywords :
HF calculations; Staebler-Wronski effect; amorphous semiconductors; bonds (chemical); defect states; electrical conductivity; elemental semiconductors; germanium; hydrogen; orbital calculations; semiconductor thin films; silicon; DV-Xα molecular orbital theory; Ge:H; Si:H; a-Si:H; amorphous semiconductor; bonding states; electrical conductivity; energy gap; energy levels; gap states; hydrogen movement; induced defects; intense light exposure; light-induced degradation; weak bond; Amorphous materials; Bonding; Degradation; Energy states; Hydrogen; Metastasis; Microscopy; Optical films; Orbital calculations; State estimation;
Conference_Titel :
Photovoltaic Energy Conversion, 1994., Conference Record of the Twenty Fourth. IEEE Photovoltaic Specialists Conference - 1994, 1994 IEEE First World Conference on
Conference_Location :
Waikoloa, HI
Print_ISBN :
0-7803-1460-3
DOI :
10.1109/WCPEC.1994.520013
