Transient photocapacitance spectroscopy of deep-levels in (001) β -Ga2O3

Abstract

Defect levels in (001) β-Ga2O3 are investigated using transient photocapacitance (TPC) spectroscopy. For sub-band photon energies in the range of 1.13–3.10 eV, the TPC signal shows broad optical absorption at room temperature. Using the theoretical Pässler model, deep-level states at E T = 1.15 ± 0.07 eV (Trap 1) and E T = 1.69 ± 0.41 eV (Trap 2) below the conduction bands are demonstrated. The Franck–Condon energies ( D F C) of Trap 1 and Trap 2 are 0.26 ± 0.11 and 0.66 ± 0.55 eV, respectively. TPC measurements have been performed at temperatures ranging from 30 to 360 K. From 150 to 360 K, the TPC signal of Trap 1 decreases as the temperature increases. The decrease in the TPC signal of Trap 1 agrees with the thermal quenching model, and a thermal activation energy of 156 meV is estimated. Moreover, the effective phonon energy of β-Ga2O3 has been extracted. From 30 to 360 K, the effective phonon energy is in the range of 85–126 meV.