Hydrogen plasma removal of AlGaAs oxides before molecular beam epitaxy

• Published in: Applied physics letters 1993-02, Vol.62 (7), p.735-737
• Main Authors: CHOQUETTE, K. D, HONG, M, CHU, S. N. G, LUFTMAN, H. S, MANNAERTS, J. P, WETZEL, R. C, FREUND, R. S
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Solid surfaces and solid-solid interfaces; Surface and interface dynamics and vibrations; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.108854

We report a method for the removal of AlxGa1−xAs native oxides for 0≤x≤1, prior to molecular beam epitaxial overgrowth. The oxides formed on epilayers of AlGaAs after atmospheric exposure are removed in an electron cyclotron resonance hydrogen plasma with a substrate temperature less than 400 °C. Reflection high energy electron diffraction indicates the plasma-prepared AlGaAs surface are oxide-free and crystalline; after a vacuum anneal to 250–500 °C, GaAs or AlGaAs are epitaxially overgrown on these surfaces. Secondary ion mass spectroscopy detects C, O, and Si impurities at the interfaces, where their concentrations increase with increasing Al content of the exposed surface. The quality of the interface and the overgrown film, as observed by transmission electron microscopy, are found to be better for lower interface impurity densities.