Gate leakage current induced trapping in AlGaN/GaN Schottky-gate HFETs and MISHFETs

Abstract

This study examined the correlation between the off-state leakage current and dynamic on-resistance (RON) transients in AlGaN/GaN heterostructure field-effect transistors (HFETs) with and without a gate insulator under various stress conditions. The RON transients in a Schottky-gate HFET (SGHFET) and metal-insulator-semiconductor HFET (MISHFET) were observed after applying various amounts of drain-source bias stress. The gate insulator in the MISHFET effectively reduced the electron injection from the gate, thereby mitigating the degradation in dynamic switching performance. However, at relaxation times exceeding 10 ms, additional detrapping occurred in both the SGHFET and MISHFET when the applied stress exceeded a critical voltage level, 50 V for the SGHFET and 60 V for MISHFET, resulting in resistive leakage current build-up and the formation of hot carriers. These high-energy carriers acted as ionized traps in the channel or buffer layers, which subsequently caused additional trapping and detrapping to occur in both HFETs during the dynamic switching test conducted.

Investigation of Bulk Traps by Conductance Method in the Deep Depletion Region of the Al2O3/GaN MOS Device

“…However, the traps (e.g., interface and bulk traps) tarnish the advantages of GaN HFETs due to the stability and reliability issues such as V TH instability [ 9 ], drain lag or gate lag [ 10 ], and power slump. Besides the surface/interface traps, the GaN power HFETs’ performance such as the breakdown voltage and dynamic on-resistance could be substantially affected by the bulk traps in GaN buffer layer in high-voltage-switching applications [ 11 , 12 ] since the high electric-field is prone to trigger the buffer traps for dynamic charging/discharging. Hence, it is of great significance to characterize the buffer traps of GaN MOS devices.…”

Improvement of Dynamic On-Resistance in GaN-Based Devices with a High-Quality In Situ SiN Passivation Layer

“…Moreover, new studies of improving the interface have been introduced such as the insertion of graphene, an AlNO layer deposited by plasma-enhanced atomic layer deposition (PEALD), and a SiON layer deposited by the PECVD, respectively [15][16][17]. However, a high density of interface trap states (D it ) in the order of ~10 13 -10 14 cm −2 eV −1 are still usually present at the dielectric/AlGaN barrier interface with these ex situ passivation layer [18][19][20][21].…”

Decreased trap density and lower current collapse in AlGaN/GaN HEMTs by adding a magnetron-sputtered AlN gate

“…However, the Schottky gate causes high gate leakage at high reverse and forward biases, which introduces signal noise and device switching losses, and limits the development of AlGaN/GaN power devices [4]. Besides, due to the presence of negative charges on the surface of AlGaN materials, the surface potential can be pulled down, increasing the onresistance [5], further depleting the two-dimensional electron gas (2DEG) channel and expanding the gate depletion region, which is described as dynamic behavior degradation or gate hysteresis, etc. To address these two issues, metal-insulatorsemiconductor (MIS) structure is an effective method to reduce gate leakage and suppress current collapse effects [6,7].…”