Electronic transport transition of hydrogenated amorphous silicon irradiated with self ions

Sato, Shinichiro; Oshima, Takeshi

Electric conductivity variations of hydrogenated amorphous silicon due to self-ion irradiation are comprehensively investigated. The anomalous enhancement of dark conductivity (DC) and photoconductivity (PC) are firstly observed due to proton irradiation, and after that both decrease with increasing the irradiation fluence. The decrease in DC and PC is ascribed to the carrier removal effect and the carrier lifetime decrease accompanied by accumulation of dangling bonds, respectively. However, further irradiation causes the loss of photoconduction and the drastic increase in DC. This indicates that the dominant conduction mechanism changes from the band transport to the hopping transport due to excessive accumulation of dangling bonds. It is concluded that the conductivity variations caused by self-ion irradiation can be systematically categorized according to the ratio of the nuclear energy deposition to the electronic energy deposition of incident ions.