Analysis of the Gate Capacitance–Voltage Characteristics in p-GaN/AlGaN/GaN Heterostructures

In this letter, we analyzed the gate capacitance characteristics in p-GaN gate/AlGaN/GaN heterostructures by using a two-junction capacitor model. First, we have observed that the C-V behavior depends on the different processing conditions of the p-GaN gate. Second, a two-junction capacitor model considering a series connection of the Schottky metal/p-GaN junction capacitor and the AlGaN barrier capacitor is proposed to explain this C-V behavior. Based on this model, the junction capacitance has an influence on the total capacitance value under a high gate bias due to the Schottky metal/p-GaN junction. Furthermore, the Mg-concentration and hole density can be extracted. The extracted hole density is consistent with the results obtained by Hall measurements.