Investigation of Ni/Au-contacts on p-GaN annealed in different atmospheres

• Published in: Journal of crystal growth 2001-09, Vol.230 (3), p.564-568
• Main Authors: Mistele, D., Fedler, F., Klausing, H., Rotter, T., Stemmer, J., Semchinova, O.K., Aderhold, J.
• Format: Article
• Language: English
• Subjects: A3. Metalorganic chemical vapor deposition; A3. Molecular beam epitaxy; B1. Gallium compounds; B1. Metals; B1. Nitrides; B2. Semiconducting III–V materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Contact resistance, contact potential; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in interface structures; Exact sciences and technology; Physics
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(01)01250-7

We investigated the effect of different annealing atmospheres on contact behaviour of Ni/Au contacts on moderately doped p-GaN layers. We used the annealing gases N 2, O 2, Ar, and forming gas (N 2/H 2) at varying annealing temperatures from 350°C to 650°C in steps of 50°C. The p-GaN samples were either metalorganic chemical vapor deposition or molecular beam epitaxy grown. Contact characterization was done after each annealing step by using the circular transmission line model. Specific contact resistances were determined to be in the low 10 −4 Ω cm 2 range for oxidized contacts. Accompanying chemical analysis using depth resolved Auger electron spectroscopy revealed that NiO was formed and Au diffused towards the interface, whereas annealing in forming gas prevented oxidation and did not lead to Ohmic behaviour.