Extraction of strained-Si metal-oxide-semiconductor field-effect transistor parameters using small signal channel conductance method

Abstract

Channel conductance has been employed to extract several important parameters such as threshold voltage, gain, effective channel length, series resistance, and mobility for strained-Si metal-oxide-semiconductor field-effect-transistors fabricated on relaxed silicon-germanium virtual substrates with Ge composition up to 25%. Analytical models have been developed by taking into account the effect of strain (i.e., Ge composition) on these parameters. The low field mobility of the devices has been found to increase linearly up to a Ge composition of 25% in the virtual substrate. A modified channel conductance technique has been used to extract critical fields accurately. This has also been used to predict the dependence of mobility on electric field in a strained-Si device. The critical field for silicon devices has been found to be 65kVcm−1, while for strained-Si devices, it has been found to decrease from 62.5 to 30kVcm−1 with increasing Ge composition (15% to 25%) in the virtual substrate. The reported results are useful for the design and simulation of strained-Si devices.