Deep level defects throughout the bandgap of (010) β-Ga2O3 detected by optically and thermally stimulated defect spectroscopy

Abstract

Deep level optical spectroscopy (DLOS) and deep level transient spectroscopy (DLTS) measurements performed on Ni/β-Ga₂O₃ Schottky diodes fabricated on unintentionally doped (010) substrates prepared by edge-defined film-fed growth revealed a rich spectrum of defect states throughout the 4.84 eV bandgap of β-Ga₂O₃. Five distinct defect states were detected at E_C − 0.62 eV, 0.82 eV, 1.00 eV, 2.16 eV, and 4.40 eV. The E_C − 0.82 eV and 4.40 eV levels are dominant, with concentrations on the order of 10¹⁶cm⁻³. The three DLTS-detected traps at E_C − 0.62 eV, 0.82 eV, and 1.00 eV are similar to traps reported in Czochralski-grown β-Ga₂O₃, [K. Irmscher et al., J. Appl. Phys. 110, 063720 (2011)], suggesting possibly common sources. The DLOS-detected states at E_C − 2.16 eV and 4.40 eV exhibit significant lattice relaxation effects in their optical transitions associated with strongly bound defects. As a consequence of this study, the Ni/β-Ga₂O₃ (010) Schottky barrier height was determined to be 1.55 eV, with good consistency achieved between different characterization techniques.