Why the photoconductivity decreases in a-SiC:H and a-SiGe:H when the amount of alloying increases

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

• Publisher: Elsevier Science
• Year: 1988
• Weight: 448 KB
• Volume: 24
• Category: Article
• ISSN: 0379-6787
• DOI: 10.1016/0379-6787(88)90049-x

✦ Synopsis

IR, pbotoconductivity, Raman and photothermal deflection spectroscopy measurements were used to probe the relationship between material quality and the amount of microsl~ucture in glow discharge deposited a-SiC:H and a-SiGe:H films. We find that the microstructure is directly responsible for the decrease in photoconductivity observed in both alloys as a function of increased alloy content. The microstrucmre does this by causing a decrease in the steepness of the Urbach tail, thus allowing for an increase in both carrier trapping at the wider band edges and carrier recombination at or near the band tails.