Deep level transient spectroscopy investigation of ultra-wide bandgap (2¯01) and (001) β -GaO

This work reports on a comprehensive examination of the electrical and thermal properties of vertical Schottky diodes fabricated on (2 ¯ 01)- and (001)-oriented samples of β-Ga2O3. The temperature-dependent current-voltage (I-V) and capacitance-voltage (C-V) data were gathered and analyzed down to 60 K. Deep level transient spectroscopy (DLTS) was used to study bulk and interface defects in the two materials from approx. 325 K down to 60 K. In the bulk (2 ¯ 01) material, an electron trap was observed at EC-0.46 eV, with a capture cross section of 1.6 × 10-14 cm2 and a lambda-corrected maximum trap density of 9.08 × 1015 cm-3. These results and others indicate that the electron trap is a strong candidate for the well-known E1 defect in β-Ga2O3 based on recent investigations. Additionally, in the (2 ¯ 01) material, the smooth modulation typical of interface states is evident at temperatures below 275 K. The (001) samples manifested what is likely the E2∗ electron trap at EC-0.68 eV, with a capture cross section of 1.64 × 10-15 cm2 and a lambda-corrected maximum trap density of 8.85 × 1015 cm-3. The presence of the E2∗ defect, in particular, is a contrast to the findings of recent DLTS investigations on β-Ga2O3, which report that E2∗ emerged only after low-energy proton irradiation. These results help to further map out the defect signatures found in β-Ga2O3 materials, which are of vital importance in the design and fabrication of future β-Ga2O3 devices.