Addition of SiF4 to standard SiH4+H2 plasma: an effective way to reduce oxygen contamination in μc‐Si:H films

Abstract

AbstractThe effect of adding of silicon tetrafluoride (SiF4) to silane (SiH4) hydrogen gas mixture on the properties of highly crystallized microcrystalline silicon (μc‐Si:H) films was studied. We found that the addition of a small amount of SiF4, with a ratio to SiH4 not exceeding 1/10, has almost no effect on deposition rate and does not affect the structure of the μc‐Si:H films, but strongly reduces oxygen incorporation into the films. Reduction of oxygen content to values below 1019 cm‐3 results in intrinsic character of the films with ratio of photo to dark conductivity about 103 in whole studied range of deposition temperatures from 175 to 250 °C in contrast to films, deposited without SiF4 addition, which show strong decrease of photosensitivity with increase of deposition temperature above 200 °C (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)