Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 4: Focussed session: Transparent conductive oxides I (jointly with HL, DS)

O 4.4: Vortrag

Montag, 14. März 2011, 12:45–13:00, WIL A317

The electronic properties of β -Ga₂O₃ — •Mansour Mohamed¹, Christoph Janowitz¹, Isaak Unger¹, Zbigniew Galazka², Justin R. Weber³, and Recardo Manzke¹ — ¹Humboldt-Universität zu Berlin, Institut für Physik, Newtonstr. 15, 12489 Berlin, Germany — ²Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, 12489 Berlin, Germany — ³Materials Department, University of California, Santa Barbara, California 93106-5050, USA

Ga₂O₃ belongs to the group of transparent conducting oxides (TCOs) with a wide band gap. It exhibits the largest band gap with E_g = 4.9 eV [1] and thus a unique transparency from the visible into the UV region. The n-type high-quality β -Ga₂O₃ single crystals were grown by the Czochralski method [2]. The crystals were characterized by different techniques (LEED, STM). The experimental valence band structure of β-Ga₂O₃ was determined by high-resolution angle-resolved photoelectron spectroscopy (ARPES) utilizing synchrotron radiation. The calculated band structure was determined using advanced density functional theory (DFT) calculations employing hybrid functionals and projector augmented wave (PAW) potentials. From theory, we obtained a direct band gap of 4.87 eV and a slightly smaller indirect band gap of 4.83 eV, with the valence-band maximum (VBM) located slightly away from the M symmetry point. The experimental band structure of β-Ga₂O₃ is compared and discussed with the theoretical calculations. The effect of changing the temperature from 300K to 20K on the experimental band structure β-Ga₂O₃ was studied.