Normally-off AlGaN/GaN MIS-HEMT with low gate leakage current using a hydrofluoric acid pre-treatment

Abstract

We demonstrate the electrical performances of an AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) with low gate leakage current (I g ). A low gate leakage current as low as the order of 10 −11 A/mm was achieved from normally-off MIS-HEMT device (V th = 2.16 V) with a partially recessed gate, fluorine treatment, and ALD Al 2 O 3 gate dielectric layer. The gate leakage current decrease is attributed to the pre-treatment of the gate region with hydrofluoric acid (HF) and deionized water (DI) solution, which acts to remove the native oxide layer and thus decrease interface traps. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) analyses demonstrate that the AlGaN surfaces are modified such that the surface roughness and native oxide introduced by the treatments used to achieve normally-off operation are remedied with the use of the pre-treatment.

Ridge-channel AlGaN/GaN normally-off high-electron mobility transistor based on epitaxial lateral overgrowth

“…the burnout of circuit systems from a fail-safe perspective and to simplify the design of driving circuits, AlGaN/GaN HEMTs with normally-off behavior are desired. Several approaches have been reported to modulate the 2DEG channel and realize normally-off operation, such as recessed-gate structure [1], hybrid MIS gate [2], fluoride-based plasma-treatment [3], thin-barrier structure [4], p-n junction gate [5], ferroelectric gate [6], and some combined approaches [7][8][9][10][11]. Besides, vertical-type mesa-gate GaN transistors and groovetype channel combining polar and nonpolar AlGaN/GaN heterostructures, utilizing etching and regrowth technologies, were also reported [12][13][14].…”