Effect of total gas pressure in sputtered hydrogenated amorphous silicon
Abstract
Hydrogenated amorphous silicon (a-Si:H) thin films are prepared using DC magnetron sputtering method at a substrate temperature of 200 °C using a plasma of argon and hydrogen gas mixture. The effects of the total gas pressure (TGP) during the deposition on structural, optical and electrical properties of the films are investigated. A decrease of the polyhydride bonding groups concentration (SiHn) is observed in FTIR spectra when the TGP increases. The optical gap remains constant. With increasing TGP the dark and photoconductivity increase, the defect density of states determined from constant photocurrent method (CPM) decreases, and the quantum efficiency mobility lifetime product (ημτ) is enhanced by a factor of more than fifty. Thus, the structural and electrical properties are enhanced by only increasing the TGP. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)