Reliability evaluation of Schottky contact of AlGaN/GaN HEMT, based on two AC voltages with different frequencies

This paper presents a reliability evaluation of Schottky contact of AlGaN/GaN HEMT. The Schottky barrier height(SBH) and ideality factor are investigated through the current-voltage (I-V) characteristics. Two kinds of ac voltages with different frequencies (10 kHz and 1 MHz) are applied on the two similar Schottky contacts of AlGaN/GaN HEMT, and the I-V curves are measured. From the measured results, we find that the SBH increases and the ideality factor decreases after the same time. The 1 MHz ac voltage applied on device leads to a more and faster increase of SBH than that of 10 kHz. And the decrease of ideality factor for 1 MHz is more than that of 10 kHz. The reverse I-V characteristics of Schottky contact of AlGaN/GaN HEMT also present a larger change for 1 MHz than that of 10 kHz. In addition, we give a simple explanation why the values of ideality factor are greater than 2.0 for both two Schottky contacts of AlGaN/GaN HEMT.