Impact of the channel thickness on the performance of ultrathin InGaAs channel MOSFET devices

InGaAs channel MOSFET devices with a channel thickness down to 3nm were fabricated and systematically characterized. Thinner channels result in improved electrostatics, however, the mobility rapidly drops to 110 cm²/Vs for the 3nm thick channel which results in significant loss of the drive current. 10 nm was found to be the optimum channel thickness with 77 mV/dec sub-threshold swing (SS). To account for the band-mixing and nonparabolicity of the III-V systems, 8-bands k.p simulations were conducted to gain an accurate insight into the device operation. As also verified experimentally, simulations suggest that the accumulation capacitance value increases as the channel thickness decreases due to the variations in the inversion charge profile. Simulations suggest that the InP buffer response affects the effective mass of the carriers and reduces the mobility as the channel becomes thinner. Based on this work, InGaAs channel thicknesses of 5nm and below hit severe performance issues.