Paramagnetic states in µc‐SiC:H thin films prepared by Hot‐Wire CVD at low temperatures

Abstract

AbstractThe relationship between the structure, electrical conductivity and paramagnetic states in microcrystalline hydrogenated silicon carbide (µc‐SiC:H) prepared by HWCVD is investigated. The study includes undoped and Al‐doped (p ‐type) µc‐SiC:H of different crystalline volume fraction (ICIR). High densities of paramagnetic states are observed in undoped material over a wide range of crystallinity whereas the conductivity increases by 10 orders of magnitude up to 10‐2 S/cm as the material becomes more crystalline. This dramatic increase of the conductivity attributed to unintentional n ‐type doping has a clear effect on the ESR spectrum which changes from a broad featureless resonance in the low crystallinity material to a sharp line with a pair of distinct satellites in highly crystalline n ‐type µc‐SiC:H. Al‐doping results in compensation and then effective p ‐type doping in µc‐SiC:H at higher doping concentration. Al‐doping seems to hinder the crystalline growth in p ‐type µc‐SiC:H. For ICIR ≤ 20% the spin resonance signature is a broad (peak‐to‐peak linewidth ΔHpp ≈ 30 G) featureless slightly asymmetric line at g ≈ 2.01. The nature and behavior of the ESR spectra in different types of µc‐SiC:H are investigated with respect to the Fermi level position and crystalline volume fraction (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)