Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 9: Poster 1
HL 9.69: Poster
Montag, 23. März 2009, 14:30–17:00, P2
Acceptor centres in Ga2O3 — •Jan Stehr1, Andreas Laufer1, Detlev M. Hofmann1, Bruno K. Meyer1, Daniel Röhrens2, and Manfred Martin2 — 1I. Physikalisches Institut, Justus-Liebig-Universität, Heinrich-Buff-Ring 16, D- 35392 Giessen — 2Institut für Physikalische Chemie, RWTH Aachen, Landoltweg 2, D- 52074
Ga2O3 is a wide band gap semiconductor (Egap = 4.9 eV) with potential applications as a TCO material (Transparent Conducting Oxide). The n-type conductivity of the undoped material is caused by the presence of oxygen vacancies which act as shallow donors. The oxygen vacancies can be introduced by heat treatments in reducing atmospheres such as ammonia. Information on the nature of the acceptors in this material is rare.
We investigated a set of Ga2O3 powder samples by electron paramagnetic resonance (EPR)
which were annealed in ammonia at 780 ∘C for 5, 18, 30 and 120 minutes. We observe 3 centres. Signal A at g = 4.3 is prominent in all samples and is attributed to residual Fe impurities. Signal B, consists of a set of two groups with 4 lines of equal intensities. The spectrum is explained by a state with S = 1/2 and I = 3/2. Possible candidates are Ga4+, Cu2+ or As0. The g-values g⊥ = 2.33 and g|| = 2.04 are typical for an acceptor centre. Signal C is the oxygen vacancy shallow donor at g = 1.96, as expected the intensity of this signal is increasing with the nitridation time. The intensity of signal B is not correlated which can be taken as evidence that it is of an extrinsic origin.