Research opportunities for nanoscale CMOS

In this paper, the authors analyze the potential performance advantages of using III-V compound semiconductors to provide high device performance. The performance of ultra-thin body double-gate FETs of various III-V compound semiconductors (GaAs, InAs, InSb) was analyzed and compared with Ge and Si. The performance limits of ultra-thin body double-gated (DG) III-V channel MOSFETs are presented in this paper. An analytical ballistic model including all the valleys (Gamma-, X- and L-), was used to simulate the source to drain current. The band-to-band (BTBT) limited off currents, including both the direct and the indirect components, were simulated using TAURUSTM. Our results show that at significantly high gate fields, the current in the III-V materials is largely carried in the heavier L-valleys than the lighter Gamma- valleys, due to the low density of states (DOS) in the Gamma, similar to current conduction in Ge. Moreover, these high mobility materials like InAs, InSb and Ge suffer from excessive BTBT which seriously limits device performance. Large bandgap III-V materials like GaAs exhibit best performance due to an ideal combination of low conductivity effective electron mass and a large bandgap.