Sensitivity Of Amorphous Silicon-Germanium Solar Cells To Oxygen Impurity Atoms

The performance of thin-film solar cells based on amorphous silicon germanium alloys (a-SiGe:H) are shown to be relatively sensitive to the contamination level of oxygen and/or nitrogen impurity atoms. Both a-SiGe single-junction solar cells and amorphous silicon (a-Si:H)/a-SiGe:H tandem solar cells were fabricated using a calibrated leak during deposition of individual layers. After light soaking, the tandem cells with a-SiGe layers deposited with an air leak, and observed to incorporate similar to4 (2.3)x10(19) cm(-3) oxygen (nitrogen) atoms, have significantly (10%) lower performance. The efficiency of a-SiGe:H single junction cells fabricated with varying air leak rates are found to improve systematically by similar to20% as the incorporated oxygen (nitrogen) concentration decreased by a factor of similar to3 (23) down to 1.3 (0.1)x10(19) cm(-3). (C) 2003 American Institute of Physics.