Comparative study of self-heating effect on electron mobility in nano-scale strained silicon-on-insulator and strained silicon grown on relaxed SiGe-on-insulator n-metal-oxide-semiconductor field-effect transistors

Abstract

From the viewpoint of the silicon thickness limit for mobility enhancement in a strained Si channel, we investigated the difference in the self-heating effect on electron mobility between strained silicon-on-insulator (sSOI) and strained Si grown on relaxed SiGe-on-insulator (epsilon-Si SGOI) n-metal-oxide-semiconductor field-effect transistors (MOSFETs) as a function of silicon thickness. We found, for the first time, by numerical simulation that when considered with the presence of self-heating in the silicon thickness range from 5 to 10 nm, the reduction in the mobility enhancement ratio of sSOI n-MOSFETs is less than that of epsilon-Si SGOI n-MOSFETs by numerical simulation. In addition, we confirmed that the quantum size effect, occurring at the peak mobility value of a 3 nm silicon thickness, disappeared in sSOI n-MOSFETs but was suppressed in epsilon-Si SGOI n-MOSFETs. Therefore, we propose that an sSOI n-MOSFET is a more promising device than a epsilon-Si SGOI n-MOSFET for high-performance devices with a design rule of less than 45 nm.