Thermal dehydrogenation of amorphous silicon deposited on c‐Si: Effect of the substrate temperature during deposition

Abstract

AbstractSamples of doped and undoped a‐Si:H were deposited at temperatures ranging from 100 ºC to 350 ºC and then submitted to different dehydrogenation temperatures (from 350 ºC to 550 ºC) and times (from 1 h to 4 h). a‐Si:H films were characterised after deposition through the measurements of specific material parameters such as: the optical gap, the conductivity at 25 ºC, the thermal activation energy of conductivity and its hydrogen content. Hydrogen content was measured after each thermal treatment. Substrate dopant contamination from phosphorus‐doped a‐Si thin films was evaluated by SIMS after complete dehydrogenation and a junction depth of 0.1 mm was obtained. Dehydrogenation results show a strong dependence of the hydrogen content of the as‐deposited film on the deposition temperature. Nevertheless, the dehydrogenation temperature seems to determine the final H content in a way almost independent from the initial content in the sample. H richer films dehydrogenate faster than films with lower hydrogen concentration (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)