Mercury-probe measurement of electron mobility in β-Ga₂O₃ using junction moderated dielectric relaxation

Abstract We demonstrate the junction-moderated dielectric relaxation method to measure the in-plane electron mobility in β -Ga 2 O 3 epitaxial layers. Unlike the Hall technique and channel mobility measurement in field-effect transistors, this method does not require the deposition of permanent metal contacts. Rather, it measures the bias voltage and frequency dependence of the equivalent capacitance of the Mercury/ β -Ga 2 O 3 /Mercury structure consisting of a Schottky contact, a quasi-neutral thin film semiconductor, and an Ohmic contact connected in series. The intrinsic dielectric relaxation of the bulk β -Ga 2 O 3 semiconductor typically occurs at ∼10 12 s −1 , but when moderated by the Mercury/ β -Ga 2 O 3 Schottky junction, it manifests itself as an inflection in the capacitance-frequency characteristics at a much lower frequency of ∼10 6 s −1 within the range of most capacitance measuring instruments. Using carrier density and layer thickness determined from capacitance-voltage measurement, we extract the electron mobility of β -Ga 2 O 3 from the junction-moderated dielectric relaxation frequency.