High performance RF power LDMOSFETs for cellular handsets formed in thick-strained-Si/relaxed-SiGe structure

We applied a strained-Si/relaxed-SiGe structure to LDMOSFETs in order to improve the power-added efficiency (PAE) of cellular handset RF power amplifier applications. Our LDMOSFETs were fabricated in a 70-nm-thick strained-Si/relaxed Si
_0.85
Ge
_0.15
structure. Despite of appearance of misfit dislocations, the thick strained-Si was essential for the high efficiency and low leakage. The self-heating effects on the power performance were estimated to be negligible by using a dynamic thermal simulation. The devices exhibited 46.7%-PAE at 27.5 dBm-P
_out
for WCDMA a handset application, which was improved by 4.0 point over Si controls