Electrical Properties, Deep Trap and Luminescence Spectra in Semi-Insulating, Czochralski β-Ga2O3 (Mg)

Abstract

The temperature dependence of conductivity, thermally stimulated current (TSC), photoinduced current transient spectroscopy (PICTS) and microcathodoluminescence (MCL) were studied for Czochralski-grown β-Ga2O3 doped with Mg. The crystals had resistivity of 4.5 × 1011 Ω.cm at 450K. The activation energy of the conductivity in the dark was 1.3 eV. TSC spectra revealed deep traps with activation energy ∼ 1 eV. In PICTS, a minor peak with activation energy ∼0.8 eV, two major peaks with activation energy 1.05 eV and 1.35 eV, and a broad band corresponding to negative photoconductivity were observed. From the dependence of the peak amplitude on bias polarity, the 1.05 eV peak was attributed to a Mg-related hole trap at Ev+1.05 eV. The higher energy peak was assigned to electron emission from a deep electron trap at Ec-1.35 eV that pins the Fermi level. Photocurrent spectra showed deep traps with optical ionization thresholds at 2 eV and 2.3 eV. MCL spectra showed the presence of traps with peak emission energies at 3.1 eV, 2.81 eV, and 2.56 eV.