We report observation of the piezoresistive effect of β-Ga 2 O 3 and investigate its application for strain gauge sensors. Ti/Au ohmic contacts are fabricated on commercially procured β-Ga 2 O 3 materials. We employ the transfer length measurement pattern to remove the influence of contact resistance on the resistance measurement of β-Ga 2 O 3 samples, especially when measuring the relatively small piezoresistance change due to strain. A gauge factor of −5.8 ± 0.1 is measured from a Ti/Au-β-Ga 2 O 3 -Ti/Au structure under tensile uniaxial stress in the [010] direction at room temperature.

The authors use isothermal capacitance transient spectroscopy to detect three deep defects located at approximately 0.6, 0.8, and 1.0 eV below the conduction band of β-Ga2O3 materials. The electrical properties of these defects such as their capture cross sections and concentrations are characterized, and their potentially adverse effects on power electronic devices are discussed. Because the isothermal capacitance transient spectroscopy method is implementable by instruments intended for steady-state capacitance-voltage measurement, it is promising for use as an effective characterization and monitoring tool for deep defects in β-Ga2O3 and other wide bandgap semiconductors.