Low frequency noise measurements on silicon-on-sapphire (SOS) MOS transistors

Measurements of the equivalent input noise are performed on P-channel silicon-on-saphire, metal-oxide-semiconductor (SOSMOS) transistors as a function of the silicon layer bias voltage with respect to the source. Devices are operated in the ohmic region of the characteristics so that the results are easier to analyse. The results show a high degree of dispersion in the noise characteristics for the different tested devices all originated from the same silicon on sapphire wafer. We conclude that a dispersion of the silicon-sapphire interface properties, such as SRH centers density or fixed positive charge, exists on the wafer. From one specific device, we calculate a fixed positive silicon-sapphire interface charge (about 4 × 10¹¹ cm^?2) and a high density (about 5 × 10¹¹ cm^?2) SRH centers localized near the silicon-sapphire interface.