Films of α-Ga2O3 doped with Sn were grown by halide vapor phase epitaxy (HVPE) on planar and patterned sapphire substrates. For planar substrates, with the same high Sn flow, the total concentration of donors was varying from 1017 cm−3 to high 1018 cm−3. The donor centers were shallow states with activation energies 35–60 meV, centers with levels near Ec–(0.1–0.14) eV (E1), and centers with levels near Ec–(0.35–0.4) eV (E2). Deeper electron traps with levels near Ec−0.6 eV (A), near Ec−0.8 eV (B), Ec−1 eV (C) were detected in capacitance or current transient spectroscopy measurements. Annealing of heavily compensated films in molecular hydrogen flow at 500 °C for 0.5 h strongly increased the concentration of the E1 states and increased the density of the E2 and A traps. For films grown on patterned substrates the growth started by the formation of the orthorhombic α-phase in the valleys of the sapphire pattern that was overgrown by the regions of laterally propagating α-phase. No improvement of the crystalline quality of the layers when using patterned substrates was detected. The electric properties, the deep traps spectra, and the effects of hydrogen treatment were similar to the case of planar samples.
The properties of regions swept by a moving dislocation in silicon crystals are experimentally studied. The peculiarities of forming traces of various types behind dislocations observed by electron microscopy and chemical etching are investigated. These traces are found to arise as result of point defect redistribution by moving dislocations and change in their structural state in a volume swept by a dislocation. It is shown that the processes mentioned enable the slip plane to assume properties of a specific two‐dimensional defect responsible for the appearance of the new mechanism of a charge carrier mobility anisotropy in the plastically deformed crystals.
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.
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