一种用于GaN HEMT中肖特基型pGaN栅极的综合寿命模型

A systematic time-dependent gate breakdown study was conducted on enhancement-mode GaN high-electron-mobility transistors (HEMTs) under various accelerated gate voltages and temperatures. Impact ionization (I.I.) was identified as the primary wearout mechanism responsible for pGaN gate breakdown failures. A comprehensive gate lifetime model, based on the I.I. mechanism, was developed to quantitatively model the voltage and temperature dependence of mean-time-to-fail (MTTF). Two distinct activation energies (E _ a ) were observed across different temperature ranges. At lower temperatures, the temperature dependent MTTF is primarily influenced by the temperature dependence of I.I. coefficients, resulting in a negative E _ a . At higher temperatures, thermionic emission (TE) becomes the dominant conduction mechanism for the gate leakage current (I _ G ). Consequently, I _ G increases exponentially with temperature, leading to considerably more hot electrons within the depleted pGaN gate layer, which accelerates the I.I. failure process. Therefore, the temperature dependence of I _ G dominates over the effect of I.I. coefficients, yielding a positive E _ a at elevated temperatures.