Photoelectrical Properties of a-Si:H Thin Films Deposited on Porous Silicon by DC-Magnetron Sputtering

Abstract

The Photoelectrical properties of hydrogenated amorphous silicon thin films (a-Si:H) deposited on porous silicon (PSi) were investigated. Porous Si layers were formed by electrochemical etching of p+-type crystalline Si in a hydrofluoric solution, whereas a-Si:H films were deposited in a partially hydrogenated atmosphere using the DC-Magnetron sputtering method. Samples with a-Si:H films deposited at different H2 flow rates and with PSi layers of different porosities and thicknesses were characterized. The Dark and under illumination I-V characteristics as well as the photocurrent response of these samples, were recorded on Al/a-Si:H/PSi/Si structures using both sandwich and planar configurations. These measurements were compared to that obtained with a-Si:H directly in contact with c-Si substrate. The results of our investigation demonstrate that the PSi layer characteristics strongly affect the photoelectrical properties of a-Si:H thin films and their influence depends on the electrical properties of these films.