Spectroscopic Detection of Medium Range Order in Device Grade Hydrogenated Amorphous Silicon

This article addresses low defect densities in hydrogenated amorphous silicon, a-Si1-x:Hx with approximately 10 at. % bonded H, x~0.1. Based low defect densities at mid-gap, ~0.5 to 1×1016 cm-3, a-Si:H thin films have been integrated into photovoltaic (PV) devices and thin film transistors (TFT's). Amorphous Si (a-Si) thin films with no detectable bonded-H have been used as precursors for polycrystalline gate electrodes in microelectronic applications. PV and TFT alloys have been deposited by glow discharge (GD), remote plasma-enhanced chemical vapor deposition (RPECVD), and reactive magnetron sputtering (RMS) with different bonded-H content determined by deposition precursors and substrate temperatures. Two conditions are required for the lowest Si dangling bond densities: (i) a monohydride, Si–H, concentration of ~10 at. % H, and (ii) deposition, and/or a post-deposition annealing at 240 to 300 °C.