We use steady-state capacitance measurement originally intended for capacitance–voltage experiment to observe and characterize the electrical properties of deep defects in β-Ga2O3 semiconductors. We detect a deep level located 0.81 eV below the conduction band edge with a concentration of 1.2 × 1016 cm−3 and a capture cross-section of 1.1 × 10−14 cm2, making it potentially influential in determining the performance of β-Ga2O3 based power electronic and optoelectronic devices. This deep level may dominate the thermal activation of off-state drain current in β-Ga2O3 transistors at high temperatures and, together with another shallower level at 0.13 eV, may substantially lower the breakdown voltage in Schottky diodes.

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.