DC performance improvement of nanochannel AlGaN/AlN/GaN HEMTs with reduced OFF-state leakage current by post-gate annealing modulation

Abstract

In this work, the effects of a post-gate annealing (PGA) treatment on the electrical performance of AlGaN/AlN/GaN nanochannel high electron mobility transistors (NC-HEMTs) were analyzed, with various channel widths of 200, 400, 600, and 800 nm for a constant fill factor of 0.45. A systematic improvement in the DC parameters was observed in the NC-HEMTs after PGA treatment at 400 • C for 10 min. Secondary ion mass spectroscopy was performed on the 300 • C, 400 • C, and 500 • C for 10 min annealed and as-deposited NC-HEMT to optimize the PGA conditions. It was also verified that annealing at higher temperatures (>400 • C) can cause the diffusion of the gate metal (Ni/Au) into the AlGaN/AlN/GaN active layer, which subsequently degrades the device performance. The removal of shallow traps after the PGA treatment, which were created by ICP dry etching, improved the Schottky barrier height (∅ B ) from 0.42 eV to 1.40 eV and resulted in a significant reduction in the reverse gate leakage current (I G ) of approximately more than three orders of magnitude in the NC-HEMT with a channel width of 200 nm. The reduction in the channel resistance after the PGA treatment, correspondingly improved the drift velocity, resulting in a marked improvement in the maximum transconductance (G MMAX ) of 34% and considerable incremental increases in the maximum drain current (I DMAX ). The NC-HEMT (W NC = 200 nm) with PGA treatment exhibited decent performance, with an I G of 9 × 10 −9 A mm −1 , an I DMAX of 470 mA mm −1 , a G MMAX of 140 mS mm −1 , and an ON/OFF ratio (I ON /I OFF ) of approximately 1.1 × 10 7 along with improved gate controllability, i.e. lowering of the subthreshold swing to 69 mV dec −1 .

Positive Shifting of Vth with Enhanced DC Performance in AlGaN/GaN Schottky-Gate HEMT through Optimized UV/O3 Treated Gate Interface and Thermal Engineering

“…6 Furthermore, from equation (1) it can be understood that, due to the incremental increase of the ∅ B after gate annealing treatment the V TH shifts significantly towards positive direction. 22 There was no significant change in V TH was found for conventional HEMT after annealing treatment.…”

“…The subthreshold drain leakage current is dominated by the reverse biased gate leakage current (I G ) in the pinch-off region. 22 Since, the I G was suppressed in SG-HEMT after UV/O 3 surface treatment and PMA modification, the subthreshold drain leakage current was decreased. The subthreshold swing (SS) was also highly dependent on the reverse biased gate leakage current.…”

“…The subthreshold swing (SS) was also highly dependent on the reverse biased gate leakage current. 22 To understand the gate controllability, the SS values of all the devices were calculated from Fig. respectively.…”

“…Previous reports also mentioned that the post metal annealing (PMA) modulation could significantly improves the Schottky barrier height (Φ B ), which subsequently reduce the gate leakage current as well as shifts the V TH towards positive direction. 22 To date, the direct observation in the positive shifting of V TH with significant reduction of gate leakage current in optimized UV/O 3 treated Schottky gate (SG)-HEMT with PMA modulation has not yet been investigated.…”

Remarkable Reduction in IG with an Explicit Investigation of the Leakage Conduction Mechanisms in a Dual Surface-Modified Al2O3/SiO2 Stack Layer AlGaN/GaN MOS-HEMT

“…GVS improved from 1.10 V to 1.92 V in the dual surface-treated stack layer MOS-HEMT after gate annealing treatment. Thus, low phase noise, device linearity, and wide dynamic range were improved after dual surface treatment and PGA modulation in the stack layer MOS-HEMT [39]. Moreover, GMMAX was 91 mS/mm in the SiO2 MOS-HEMT.…”