Low Resistance CrB2/Ti/Al Ohmic Contacts to N-face n-GaN for High Power GaN-Based Vertical Light Emitting Diodes

Abstract

We investigated the effect of a CrB2 interlayer on the electrical properties of Ti/Al contacts to N-face n-type GaN for high performance vertical light emitting diodes. Before annealing, both CrB2 (30 nm)/Ti (30 nm)/Al (200 nm) and Ti (30 nm)/Al (200 nm) contacts produce ohmic behaviors with a contact resistivity of 1.92 x 10(-4) and 1.99 x 10(-4) Omega cm(2), respectively. Unlike the Ti/Al contacts, however, the CrB2/Ti/Al contacts remain ohmic with a contact resistivity of 8.30 x 10(-4) Omega cm(2) even after annealing at 250 degrees C for 1 min in N-2 ambient. X-ray photoemission spectroscopy and secondary-ion mass spectrometry examinations are performed to describe the ohmic formation behavior. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3461136] All rights reserved.