Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 16: GaN: Bauelemente
HL 16.6: Vortrag
Dienstag, 9. März 2004, 11:30–11:45, H13
Improvement of GaN Schottky Diodes by Thermal Oxidation — •Olaf Weidemann1, Eva Monroy2, Eike Hahn3, Martin Hermann1, Edgar Zaus1, Martin Stutzmann1, and Martin Eickhoff1 — 1Walter Schottky Institut, TU München, 85748 Garching — 2CEA-CNRS-UJF Nanophysique et Semiconducteurs, CEA-Grenoble, 38054 Grenoble, France — 3Laboratorium für Elektronenmikroskopie, Universität Karlsruhe, 76128 Karlsruhe
GaN Schottky contacts have gathered increasing interest for the application as UV detectors and, more recently, as high temperature gas sensitive devices and GasFETs with catalytic Schottky contacts. However, Schottky contacts on GaN suffer from high reverse currents due to the presence of threading dislocations. To improve the device characteristics and to guarantee reproducible electronic properties, a passivation of these defects is desirable.
We have investigated the effect of thermal oxidation on the electronic characteristics of Schottky contacts on heteroepitaxial n- and p-type GaN layers grown by plasma assisted molecular beam epitaxy. Thermal oxidation was found to lead to significant device improvement, notably a decrease in reverse leakage current and an enhanced rectification ratio, which has been quantified by IV- and CV-measurements. Analysis of the oxidized layers by TEM and AFM revealed that preferential oxidation at crystal defects is the dominating mechanism for the observed device improvement.