Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 17: Poster Session I

DS 17.21: Poster

Tuesday, March 13, 2018, 18:15–20:15, Poster B

Electrical charcterization of thin monocrystalline homoepitaxial β-Ga₂O₃ films — •Robin Ahrling¹, Johannes Boy¹, Martin Handwerg¹, Rüdiger Mitdank¹, Zbigniew Galazka², Günter Wagner², and Saskia F. Fischer¹ — ¹Novel Materials Group, Humboldt-Universität zu Berlin, 12489 Berlin, Germany — ²Leibniz Institute for Crystal Growth, 12489 Germany

As a wide band gap semiconductor with a high breakthrough field, gallium oxide (Ga₂O₃) has shown to be a promising material for applications in high power electronics. However, it is not yet clear how its electrical properties may change with a variation of crystal thickness. These changes may be caused by a change in scattering mechanisms or an inhomogeneity in crystal growth.

Here, homoepitaxially MOVPE-grown monocrystalline Si-doped β-Ga₂O₃ films of thicknesses between 28 nm and 225 nm were electrically characterized in a temperature range from 300 K down to 10 K. Van-der-Pauw and Hall-measurements have been performed to determine conductivity, Hall density and carrier mobility in those films. It was found that above 150 nm thickness the films show a behavior similar to the bulk. Below 100 nm a drastic drop of the mobility with decreasing thickness was seen. The Bergmann model, based on surface scattering of electrons due to their wavelength, was used to describe this dependence and showed an overall good agreement with the data. An alternative explanation is inhomogeneity in the sample growth process. In any case, this reduction in mobility for thin films has to be considered for future applications in devices.