Effect of thermal annealing on electrical and structural properties of Ni/Au/n-GaN Schottky contacts

• Published in: Microelectronic engineering Vol. 130; pp. 62 - 68
• Main Authors: Akkaya, A., Esmer, L., Kantar, B. Boyarbay, Çetin, H., Ayyıldız, E.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.11.2014; Elsevier
• Subjects: Annealing; Applied sciences; Atomic force microscopy; Barrier inhomogeneity; Barriers; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); 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; Electrical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronics; Exact sciences and technology; Gallium nitrides; GaN; Gold; Interfaces; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nickel; Photolithography; Physics; Schottky barrier height; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Surface double layers, schottky barriers, and work functions; Thermal annealing; Treatment of materials and its effects on microstructure and properties; Volt-ampere characteristics; X-ray photoelectron spectroscopy; XPS; Barrier inhomogeneity; XPS; Electrical properties; Thermal annealing; Schottky barrier height; GaN; Atomic force microscopy; Electric contacts; Schottky barriers; Metallizing; Annealing temperature; Gallium nitride; CV characteristic; Ideality; CaN; Microelectronic fabrication; n type semiconductor; Chemical composition; Photolithography; IV characteristic; Depth profiles; Electrical characteristic; Aluminium oxide; Binary compounds; MOCVD; III-V compound; CVD; Lift off; Inhomogeneity; Nickel; Barrier height; X-ray photoelectron spectra
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2014.10.003

[Display omitted] •The effects of thermal annealing on Ni/Au contacts were investigated.•The metallization patterns were formed using the photolithography technique.•The chemical composition of the contacts was examined by XPS.•The leakage current after annealing was improved by two orders of magnitude. The effects of thermal annealing on the electrical and structural properties of Ni/Au Schottky contacts to n-type GaN were investigated by current–voltage (I–V) and capacitance–voltage (C–V) characteristics, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) depth profile analysis. The metallization patterns on GaN grown by metal organic chemical vapor deposition (MOCVD) on a (0001) sapphire substrate were formed using the photolithography and lift-off techniques. The Schottky barrier height (SBH) for these contacts was obtained from I–V and C–V measurements. The value of SBH of the as-deposited contacts was found to be 0.560±0.004eV (from I–V) and 0.622±0.018eV (from C–V) with an ideality factor of 1.856±0.085. The values of SBH obtained from the C–V measurements were found to be higher than that of obtained from the I–V measurements. This case was attributed to the presence of the lateral inhomogeneities of the barrier height. However, the values of SBH slightly increase after the annealing temperatures at 100, 200, 300, 400 and 500°C. The SBH of the Ni/Au Schottky contact for the other annealing temperature of 600°C was 0.617±0.005eV. The highest value of SBH for Ni/Au Schottky contact was obtained after annealing at 700°C and the value was 0.910±0.019eV. The variations in the chemical composition of the contacts with the annealing process were examined by XPS depth profile analysis.