Ohmic contacts on p-GaN (Part II): impact of semiconductor fabrication andsurface treatment

The impact of p-GaN fabrication and epi-layer surface treatment on the resu lting electrical properties of ohmic contacts has been investigated. The I- V characteristics of ohmic Ni/Au and Pd contacts were determined on tempere d CTLM structures using five different types of p-GaN. Various surface trea tments of p-GaN epi-layers were also studied. No material class (MBE, MOCVD ) has been found to be superior to the other, although strong differences i n electrical properties between the various sample types were obtained. In contrast to that, the impact of different surface treatment methods on the electrical contact properties was found to be low. However, some treatments damaged the p-GaN epilayer heavily, no ohmic contacts could be obtained on these samples. (C) 2001 Elsevier Science Ltd. All rights reserved.