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HL: Fachverband Halbleiterphysik

HL 31: Poster I: Devices, Quantum Dots and Quantum Wires

HL 31.14: Poster

Dienstag, 23. März 2010, 18:30–20:30, Poster D1

Analysis of contact resistance for p-type GaN — •Majdi Salman, Uwe Rossow, and Andreas Hangleiter — Institut für Angewandte Physik, TU Braunschweig

The overall efficiency of optoelectronic devices such as light emitting diodes (LEDs) or laser diodes (LDs) is strongly affected by the contact resistance of metal contacts, in particular at high current densities. To measure the contact resistance, one typically uses the “transmission line method” (TLM) with rectangular contact geometry or Reeves’ CTLM method with circular contacts. In this contribution we study the impact of the rather high resistivity of typical p-type GaN layers on the TLM or CTLM analysis. Using state-of-the-art MOVPE-grown p-type GaN layers with specific resistivities down to 0.8 Ωcm together with Ni/Au- and Pt-based contacts we investigate the influence of the contact geometry, the specific resistivity of the p-GaN layer, and the thickness of the p-type layer on the TLM results. We discuss a simple model explaining the experimental results.