Evaluation of Electron Trapping Speed of AlGaN/GaN HEMT With Real-Time Electroluminescence and Pulsed $I{-}V$ Measurements

A methodology for the evaluation of the electron trapping speed by combining real-time electroluminescence and the ON-resistance is proposed. In real-time electroluminescence measurements with the high sensitivity of a silicon-intensified CCD with low noise characteristics, a shift of the luminescence location from the gate edge to the drain edge was observed even while the device was under continuous biasing. This shift results from the alleviation of an electric field at the gate edge, and an alternative high electric field is produced at the drain edge. Although a drain current was almost stable even when the position of the electroluminescence was shifting, the ON-resistance significantly increased in pulsed I-V measurements. Using device simulation, we estimated dependence of the ON-resistance on the density of trapped electrons at the AlGaN surface. From measured and simulated results, the electron-trapping speed is supposed to be approximately 1×10¹⁰ cm^-2 s^-1 in the case of the AlGaN/GaN HEMT with a 2.0- μm-long gate under V_d and Vg of 10 and 0 V, respectively.