Effects of surface treatments and metal work functions on electrical properties at p-GaN/metal interfaces

• DOI: 10.1063/1.363912
• Publication Date: 2002-07-26T12:35:59Z
• Authors: Hidenori Ishikawa; Setsuko Kobayashi; Y. Koide; S. Yamasaki; S. Nagai; J. Umezaki; M. Koike; Masanori Murakami
• Keywords: Ohmic contact; Contact resistance; Electrical contacts

In order to examine the possibility of preparing a nonreacted (nonalloyed) Ohmic contact p-GaN, effects GaN surface treatments and work functions metals on electrical properties between metal contacts p-GaN were investigated. A contamination layer consisting GaOx adsorbed carbons was found substrate grown by metalorganic chemical vapor deposition. The not completely removed sputtering with Ar N ions where ion densities ∼10−2 μA/cm2. Although partially immersing in buffered HF solution, little improvement GaN/metal interfaces obtained. Most annealing Ni Ta at temperatures close 500 °C. These annealed exhibited slightly enhanced current injection from GaN. present treatment study indicated that removal did significantly reduce resistance. On other hand, resistance decreased exponentially increasing functions, Pt, Ni, Pd, Au, Cu, Ti, Al, Ta, Ni/Au deposited This result suggests Schottky barrier height p-GaN/metal interface might be pinned surface. concluded large function is desirable for p-GaN. However, these provide low required blue laser diodes.