- Study of Gate Leakage Current on AlGaN/GaN MOS-HEMTs with Atomic Layer Deposited Al2O3 Gate Oxide
We have investigated the current transport mechanism of both the reverse and forward gate leakage currents in Au/Ni/Al2O3/AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with the current-voltage (I?V) characteristics in the temperature range of 300?400 K. The room temperature capacitance-voltage (C?V) characteristics revealed a two-step capacitance change, which is the characteristic feature of the MOS-HEMT structure having two interfaces. An analysis of reverse gate leakage current of the Au/Ni/Al2O3/AlGaN/GaN MOS structure indicated the dominance of Poole-Frenkel emission mechanism and Schottky emission mechanism in the lower and higher bias regions, regardless of the temperature. The forward log I?log V plot of the Au/Ni/Al2O3/AlGaN/GaN MOS structure exhibited two different regions having different slopes, implying the domination of different conduction mechanisms in each region. At higher forward bias, the space-charge-limited current conduction mechanism dominated the current transport indicating the presence of traps with most of the traps being deep traps with trap energy Et? 0.17 eV as determined from the plot of exponent m versus the reciprocal of temperature.