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HL: Fachverband Halbleiterphysik

HL 9: Focus Session: Oxide Semiconductors for Novel Devices II

HL 9.2: Vortrag

Montag, 1. April 2019, 15:15–15:30, H34

Effective electron mass anisotropy in α-Ga₂O₃ — •Martin Feneberg¹, Jürgen Bläsing¹, Rüdiger Goldhahn¹, and Kazuaki Akaiwa² — ¹Institut für Physik, Otto-von-Guericke-Universität Magdeburg — ²Department of Information and Electronics, Tottori University, Tottori 680-8552, Japan

Metastable α-Ga₂O₃ is a currently discussed candidate material system for future electronic devices. It is alloyable with corundum α-Al₂O₃ (sapphire) and α-In₂O₃. While p-type doping proves to be problematic, n-type doping by the substitutional donor tin is successful up to n>10¹⁹ cm⁻³.

Here, we investigate the infrared optical properties of m-plane (1100) α-Ga₂O₃ thin films grown on sapphire by mist chemical vapour epitaxy. Spectroscopic ellipsometry and Raman spectroscopy yields a full picture of the anisotropic phonon modes. A free-carrier contribution in degenerately highly doped material is found in the dielectric functions and yields anisotropic plasma frequencies.

By taking the Hall-effect free-electron concentration into account, effective electron masses of m_⊥^*= 0.297 m₀ and m_||^* = 0.316 m₀ are obtained at n=1.1× 10¹⁹ cm⁻³. We finally discuss the nonparabolic dispersion relation of the conduction band rendering these values to be upper limits for the effective masses at the Γ-point of the Brillouin zone.