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

• Published in: Japanese Journal of Applied Physics Vol. 63; no. 10; pp. 101002 - 101007
• Main Authors: Li, Jian V., Kim, Yunjo, Charnas, Adam R., Noesges, Brenton A., Evans, Prescott E., Asel, Thaddeus J., Neal, Adam T., Gorsak, Cameron A., Nair, Hari P., Mou, Shin
• Format: Journal Article
• Language: English
• Published: Tokyo IOP Publishing 01.10.2024; Japanese Journal of Applied Physics
• Subjects: Capacitance; Carrier density; Contact resistance; Dielectric relaxation; Electrical measurement; Electron mobility; Epitaxial layers; Field effect transistors; gallium oxide; Gallium oxides; Measuring instruments; mercury probe; mobility; Relaxation method (mathematics); semiconductor; Semiconductor devices; Thickness measurement; Thin films
• ISSN: 0021-4922; 1347-4065
• DOI: 10.35848/1347-4065/ad8531

We demonstrate the junction-moderated dielectric relaxation method to measure the in-plane electron mobility in β-Ga2O3 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-Ga2O3/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-Ga2O3 semiconductor typically occurs at ∼1012 s−1, but when moderated by the Mercury/β-Ga2O3 Schottky junction, it manifests itself as an inflection in the capacitance-frequency characteristics at a much lower frequency of ∼106 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-Ga2O3 from the junction-moderated dielectric relaxation frequency.