1/f Noise Characteristics of AlGaN/GaN FinFETs with and without TMAH surface treatment

Abstract

In this paper, we have fabricated and investigated the AlGaN/GaN fin-shaped field-effect transistors (FinFETs) with and without TMAH surface treatment. DC and noise characteristics of the FinFETs were compared to evaluate the interface quality between Al2O3 layer and the side-wall GaN surface. The tetramethyl ammonium hydroxide (TMAH)-treated device with a fin width of 70nm and gate length, Lg=5μm exhibited excellent device performances, such as drain current of 0.16mA and transconductance (gm) of 0.11ms, both 30% improved, and extremely small gate leakage current of about 10−9A at Vgs=−5V which is approximately two orders lower in magnitude compared to that of the device without TMAH treatment. Improved low-frequency noise performances were obtained for TMAH treated device due to the enhanced side-wall quality after the TMAH surface treatment. The trap density was found to be reduced approximately one order after TMAH treatment. Thus, simple surface treatment not only smoothens the sidewall surface but also eliminates the plasma damage caused during the fin etching, which leads to the reduction of trap density in AlGaN/GaN FinFETs.