Impact of substrate-surface potential on the performance of RF power LDMOSFETs on high-resistivity SOI

Abstract

This paper presents an in-depth study of the effects of substrate-surface potential on the RF power performance of laterally diffused MOSFETs (LDMOSFETs) fabricated on high-resistivity silicon-on-insulator (HR-SOI). Substrate-surface inversion and accumulation substantially degrade the RF power performance of these devices by providing an RF shunt between source and drain through the substrate surface. The degradation is most prominent under conditions of low gain, high frequency, and high power compression. The potential of HR-SOI for RF applications can only be realized by preventing the appearance of a continuous conducting path at the substrate surface. Under appropriate conditions of substrate-surface depletion, an RF power LDMOSFET on HR-SOI with a peak PAE of 40% at 7.2 GHz is demonstrated