Defect dependence of electrical characteristics of β-Ga2O3 Schottky barrier diodes grown with hydride vapor phase epitaxy

Abstract

We investigated the electrical properties and defects of β-Ga2O3 epilayers grown at different growth rates on Sn-doped β-Ga2O3 substrates by hydride vapor phase epitaxy. The growth rates used were 0.15 and 0.25 μm/min, respectively. The crystallinity of epilayers grown by HVPE was measured by X-ray diffraction. Pd-based Schottky barrier diodes were fabricated to analyze the electrical characteristics, and defect states were studied using DLTS. The carrier concentrations of epilayers grown at the growth rates of 0.15 and 0.25 μm/min measured by C–V profiling were 4 × 1016 cm-3 and 1 × 1017 cm-3, respectively. The breakdown voltages for the β-Ga2O3 with low and high growth rates were -401 V and -132 V, respectively. The DLTS analysis revealed that three electron traps, E1 (Ec-1.04 eV), E2 (Ec-0.89 eV), and E4 (Ec-0.20 eV) in the epilayer grown at high growth rates were observed at 150 K, 375 K, and 450 K, respectively. In contrast, electron trap E3 (Ec-0.54 eV) and hole trap H1 (Ev+1.33 eV) in the epilayer grown at a low growth rate were observed at 300 K and 425 K, respectively. The total trap density of the epilayer grown at a low growth rate was 3.68 × 1013 cm-3. In contrast, the epilayer grown at a high growth rate was 2.03 × 1014 cm-3, indicating that the defect density was about 10 times higher in the epilayer grown at high growth rate. This means that the electrical characteristics of the β-Ga2O3 Schottky barrier diode are excellent when the defect density is low.