Berlin 2008 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 50: ZnO: Tansport
HL 50.5: Talk
Thursday, February 28, 2008, 15:00–15:15, ER 164
Electrical characterisation of oxygen implanted ZnO thin films. — •Matthias Schmidt1, Gerhard Brauer1, Wolfgang Skorupa1, Manfred Helm1, Holger v. Wenckstern2, Rainer Pickenhain2, and Marius Grundmann2 — 1Forschungszentrum Dresden – Rossendorf e.V., Dresden, Germany — 2Universität Leipzig, Leipzig, Germany
Since the achievement of reproducible p–type conduction is a premise for ZnO devices, it is necessary to minimize the donor–like defects causing n–type conduction. Up to now it is under discussion whether intrinsic defects like vacancies or unintentionally incorporated dopants like hydrogen or group three elements are the main source of donors.
In this work we set out to detect donor–like defects which have their origin in oxygen excess or deficiency. In order to generate only intrinsic defects and to minimize oxygen vacancies we implanted oxygen ions into ZnO thin films grown by pulsed laser deposition. After thermal annealing, rectifying palladium contacts were deposited. The rectifying behaviour of the samples has been characterized by current– voltage, and capacitance – voltage measurements. Trap concentrations and energetical depths were obtained from deep level transient–, and thermal – admittance – spectroscopy. In the oxygen implanted samples we found a trap with an energetical depth between 500 meV and 600 meV which was not detectable in virgin samples.