A measurement methodology involving the synchronous switching of gate to source voltage and drain to source voltage (VDS) was proposed for determining the shift of threshold voltage after an AlGaN/GaN heterostructure transistor endures high VDS off-state stress. The measurement results indicated slow electron detrapping behavior. The trap level was determined as (EC – 0.6 eV). Simulation tool was used to analyze the measurement results. The simulation results were consistent with the experimental results; and a relationship between the buffer trap and threshold voltage shift over time was observed.

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.

A measurement methodology involving high-voltage capacitance-voltage (C-V ) was proposed to determine the trapping profile of a stressed AlGaN/GaN heterostructure field-effect transistor (HFET). Comparing the curves between initial (device without stress) and stressed (device with stress) C-V measurements revealed that the transient behavior was dominated by ionized acceptor-like traps, and the trapping profile within the high drain-to-source OFF-state stressed AlGaN/GaN HFET could be deduced.Index Terms-AlGaN/GaN heterostructure field-effect transistors (HFETs), current collapse, transient capacitancevoltage (C-V ) measurement.

Publisher's Note: "The behavior of off-state stress-induced electrons trapped at the buffer layer in AlGaN/GaN heterostructure field effect transistors" [Appl. Phys. Lett. 104, 033503 (2014)]

No abstract