Optical absorption and disorder in hydrogenated amorphous SiGe and SiC alloy systems

✍ Scribed by R Tsu; P Menna; A.H Mahan

• Publisher: Elsevier Science
• Year: 1987
• Weight: 237 KB
• Volume: 21
• Category: Article
• ISSN: 0379-6787
• DOI: 10.1016/0379-6787(87)90118-9

✦ Synopsis

The slope of (ah¢o) 1/2 vs. h¢o depends on the product of the oscillator strength of the transition, the deformation potential and the mean deviation of the atomic coordinates. In a perfect crystal, this deviation is characterized by phonons, whereas in amorphous silicon (a-Si) and amorphous germanium (a-Ge) it is characterized by the mean bond angle distribution. We have used this slope to characterize disorder in a-Si-Ge:H and a-Si-C:H alloy systems. The Urbach edge and gap states obtained by photothermal deflection spectroscopy are included for comparison.