Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 35: New Materials: Optoelectronic and Photovoltaic Applications
HL 35.1: Talk
Wednesday, March 24, 2010, 09:30–09:45, H13
Characterization of β −Ga2O3 single crystals — •Jan Stehr1, Albrecht Hofstaetter1, Detlev Hofmann1, Bruno K. Meyer1, and Reinhard Uecker2 — 1I. Physikalisches Institut, Justus-Liebig-Universität, Heirich-Buff-Ring 16, D- 35392 Giessen — 2Leibniz-Institut für Kristallzüchtung, Max-Born-Strasse 2, D- 12489 Berlin
Ga2O3 is a wide band gap semiconductor with potential applications as transparent conducting oxide (TCO). β −Ga2O3 is typically an n-type conducting material due to oxygen vacancies, which act as shallow donors. To control the electrical properties of the material it is thus necessary to study defects and impurities in the material.
A β −Ga2O3 crystal was investigated by optical measurements and magnetic resonance spectroscopy. The band gap energy determined by UV-VIS spectroscopy is 4.6 eV parallel to the b-axis and 4.3 eV parallel to the c-axis at room temperature; we followed its dependence down to liquid helium temperature. By electron paramagnetic resonance we observe 3 signals (Signal A, B and C). Signal A consist of 8 lines with equal intensity therefore I = 7/2 is attributed to Co. Signal B shows a single line and is anisotropic, the g-value moves in angular dependent measurements from g=2.4 to g=1.5. Signal C with g=1.96 is the well known resonance of the oxygen vacancies causing the shallow donors in Ga2O3.