Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 67: Focus Session (Posters): Crystalline n-type semiconducting oxides - SnO2, Ga2O3, and In2O3 for novel devices
HL 67.4: Poster
Wednesday, March 13, 2013, 16:00–20:00, Poster A
Low Rate Deep Level Transient Spectroscopy: A new method for detecting deep levels in wide gap semiconductors — •Rainer Pickenhain1, Florian Schmidt1, Otwin Breitenstein2, Holger von Wenckstern1, and Marius Grundmann1 — 1Universität Leipzig, Institut für Experimentelle Physik II, Abteilung Halbleiterphysik, Linnéstraße 5, 04103 Leipzig — 2Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D - 06120 Halle
Deep level transient spectroscopy (DLTS) has been widely applied to study defect states within the entire bandgap of various semiconductors. The method typically uses time windows in the kHz regime which is not sufficient to study defect states in the entire bandgap of wide bandgap materials such as ZnO. In these materials the emission rates of deep defects are too low to be detected by standard DLTS. Optical DLTS (ODLTS) fails because the photon flux of conventional light sources is too small in order to shift the optical emission rates towards the kHz regime. In this contribution we propose a method (LR-ODLTS) allowing the measurement of capacitance transients in the mHz range maintaining high sensitivity. The method is applied to ZnO and first results will be presented demonstrating that LR-DLTS allows to construct experimental Arrhenius-plots of defects exceeding the emission rate span of conventional ones more than three orders of magnitude. On this basis we easily separated signals from the close-lying defects E3 and E3’ in ZnO. Furthermore several defects states within the vicinity of the valance band and close to mid gap in ZnO were detected by LR-ODLTS and will be discussed.