Effects of thermal annealing on the electrical and structural properties of Pt/Mo Schottky contacts on n-type GaN

• Published in: Journal of materials science. Materials in electronics 2009-10, Vol.20 (10), p.1018-1025
• Main Authors: Reddy, Varra Rajagopal, Ravinandan, M., Koteswara Rao, P., Choi, Chel-Jong
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Diodes; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronics; Exact sciences and technology; Interfaces; Materials Science; Optical and Electronic Materials; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Spectrum analysis; Surface double layers, schottky barriers, and work functions; Temperature effects; Treatment of materials and its effects on microstructure and properties; X-rays
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-008-9824-9

Thermal annealing temperature effects on the electrical and structural properties of platinum/molybdenum (Pt/Mo) Schottky contacts on n-type GaN have been investigated by current–voltage (I–V), capacitance–voltage (C–V), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. As-deposited Pt/Mo/n-GaN Schottky diode exhibits barrier height of 0.75 eV (I–V) and 0.82 eV (C–V). Upon annealing at 400 and 500 °C, the barrier height slightly increased to 0.77 eV (I–V) and 0.92 eV (C–V) and 0.82 eV (I–V) and 0.97 eV (C–V), respectively. A maximum barrier height of 0.83 eV (I–V) and 0.99 eV (C–V) is obtained on the Pt/Mo contacts annealed at 600 °C. X-ray photoelectron spectroscopy results shows that the Ga 2p core-level shift towards the low-energy side for the contact annealed at 600 °C as compared to the as-deposited one. Based on the results of XPS and XRD studies, the formation of gallide phases at Pt/Mo/n-GaN interface could be the reason for the increase of Schottky barrier heights upon annealing at elevated temperatures. The atomic force microscopy (AFM) results showed that the Pt/Mo contact does not seriously suffer from thermal degradation during annealing even at 600 °C (RMS roughness of 5.41 nm). These results make Pt/Mo Schottky contacts attractive for high temperature device applications.