Dependence of Device Performances on Fin Ratios of AlGaN/GaN Nanoscale Fin-HEMTs

Abstract

We report the fabrication and characterization of AlGaN/GaN fin-type high electron mobility transistors (Fin-HEMTs) grown on high-resistance silicon substrates. The Fin-HEMTs have a gate length of 125 nm by using electron-beam lithography with various fin ratios, which are defined as the total effective periodic gate widths over the gate width, along the whole gate width. The Fin-HEMTs are designed with three fin ratios of 0.5, 0.3, and 0.25. The on-resistance decreases with reducing the fin ratio and reaches 1.1 Ω-mm at the fin ratio of 0.25. In addition, the Fin-HEMT with a fin ratio of 0.25 still exhibits a 14% higher drain current density than the planar device. With tetramethylammonium hydroxide etching, the current collapse caused by surface traps on the fin’s sidewalls is significantly reduced from 28.9% to 2.4% by the pulse I-V measurement. The Fin-HEMTs also can improve the gate control capability through the analyses of small-signal and large-signal measurements.