Self-heating-induced junctionless stacked nanosheet FET RF stability performance degradation analysis and optimization

Abstract

Junctionless stacked nanosheet FETs (JL-SNSHFETs) are advanced devices with uniformly doped active regions, offering a wider effective channel width, improved electrostatics, and reduced short-channel effects (SCEs). However, self-heating is the major concern in nanosheet FETs, negatively impacting the device's performance. RF stability is critical for devices operating in the radio frequency range, as self-heating can significantly affect it. This work presents the insights meticulously investigated using the Synopsys Sentaurus TCAD tool on the impact of self-heating on the RF stability performance of JL-SNSHFET for different geometrical parameter variations of the device. The increase in nanosheet width and thickness increases the effective channel width and thereby increases the on-current; however, it also elevates the lattice temperature due to self-heating, which, in turn, deteriorates the RF stability. A ~ 10% difference in critical frequency is observed with and without self-heating. The proposed optimized JL-SNSHFET achieves an improved f_T of 145 GHz and f_max of 340 GHz, becoming unconditionally stable beyond the critical frequency of 170 GHz without any stabilization network. The propounded findings expedite the RF circuit design where self-heating is a major concern.