Surface photovoltage method for silicon-sapphire interface monitoring

Surface photovoltage (SPV) method was used to evaluate the silicon-sapphire interface potential barrier of silicon on sapphire (SOS) wafers obtained by CVD technique. The method provides monitoring of silicon-sapphire interface quality. Fabrication process parameters which influence on SPV signal were found. Silicon deposition temperature has a great importance on SPV signal. It was found that SPV method can be used as monitoring method of SOS fabrication process, because SPV signals are correlated with X-ray reflectometry results. Probably, SPV method is allowed to evaluate the structural and electrophysical parameters of silicon-sapphire interface. SOS device performances as function of SPV signal were determined. It was concluded that MOSFETs fabricated on SOS wafers with SPV signal above 450 mV had poor performance and MOSFETs fabricated on SOS wafers with SPV signal in range 120–320 mV had good performance.