Electrical characteristics of thermal sprayed silicon coatings

Polycrystalline silicon deposits were formed on a monocrystalline silicon substrate by thermal spraying. The resulting structure exhibits a device characteristic. Pressure-induced transformations of silicon, namely, Si-III (BC-8) and Si-IX are identified by X-ray diffraction in a Si-I matrix on deposits formed by vacuum plasma spray. The presence of the Si-III and Si-IX indicates that the pressure-quenched silicon deposit is highly conductive, as determined by four-point van der Pauw resistivity measurement. Hall mobility measurements, combined with photoconductivity results, indicate that the highly conductive silicon deposit displays the same range of mobility as a polycrystalline deposit containing only Si-I. The silicon deposit, with or without metastable phases, displays the same photoconductivity properties. The silicon deposit on a monocrystalline silicon substrate exhibits rectifying I-V characteristics, possibly caused by band bending of trapping states associated with impurities segregating at the polycrystalline deposit/monocrystalline substrate interface.