Deep level transient spectroscopy investigation of ultra-wide bandgap (201) and (001) β-Ga2O3

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.