Admittance Spectroscopy Study of Defects in β-Ga2O3

Abstract

We present a comprehensive investigation of electrically active defects and transport properties in commercial (2¯01) edge-defined film-fed growth β-Ga2O3 using admittance spectroscopy measurements from 14 K up to 450 K. Isothermal capacitance-frequency measurements were conducted from 410 to 450 K to resolve a defect ∼0.8 eV below the conduction band edge and compared with deep-level transient spectroscopy and isothermal capacitance transient spectroscopy measurements. We report significant non-Arrhenius behavior of a defect ∼100 meV below the conduction band and apply the Arrhenius transformation matching method to extract its temperature-dependent activation energy and capture cross-section in the temperature range of 75 to 195 K. At low temperatures (<50 K), we use bias-dependent admittance spectroscopy to extract the electron mobility in β-Ga2O3 from the modified dielectric relaxation frequency. Finally, we discuss the potential of admittance spectroscopy for defect characterization in wide bandgap semiconductors in terms of the defect detection range, instrument requirements, and the frequency-temperature experiment space.