Low-resistance contacts with chemical vapor deposited tungsten on GaAs grown by molecular layer epitaxy

• Published in: Journal of the Electrochemical Society Vol. 146; no. 1; pp. 131 - 136
• Main Authors: OYAMA, Y, PLOTKA, P, MATSUMOTO, F, KURABAYASHI, T, HAMANO, T, KIKUCHI, H, NISHIZAWA, J.-I
• Format: Journal Article
• Language: English
• Published: Pennington, NJ Electrochemical Society 1999
• Subjects: Applied sciences; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electrical properties of specific thin films; Electrical properties of specific thin films and layer structures (multilayers, superlattices, quantum wells, wires, and dots); Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Materials science; Metals. Metallurgy; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Gallium arsenides; Atomic layer method; RBS; Inorganic compounds; Semiconductor materials; Epitaxy; Binary compounds; Contact resistance; Crystal growth from vapors; Solid-solid interfaces; Experimental study; Metal-semiconductor contacts; Thin films; CVD; Transition elements; Tungsten; SIMS
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1391575

Approximately 100 A thick, mirror-like, ordered tungsten layers were fabricated on (100) GaAs with chemical vapor deposition, using a W(CO) sub 6 precursor. Native oxides on GaAs were reduced with AsH sub 3 pretreatment in a chemical vapor deposition chamber of tungsten. Secondary ion mass spectrometry and Rutherford backscattering spectroscopy analyses indicate tungsten-GaAs mixed layer not thicker than 20 A. The chemical vapor deposited tungsten was applied to fabrication of state of the art, low resistance contacts to GaAs layers grown with molecular layer epitaxy. Optimization of GaAs doping, pretreatment, and tungsten chemical vapor deposition conditions were necessary to obtain low contact resistance. Contact resistance, measured with the transmission line method, was 3x10 exp -7 Omega cm exp 2 to Te doped n-type GaAs and below 2x10 exp -8 Omega cm exp 2 to C doped p-type GaAs. Electrically active donor/acceptor concentrations in GaAs layers grown by molecular layer epitaxy were about one order of magnitude lower than expected from literature trend lines for these contact resistance.