New Ge substrate cleaning method for Si_1-x-yGe_xC_y MOMBE growth

摘要

A new method of cleaning a Ge wafer based on a wet chemical treatment and Si_1-x-yGe_xC_y/Ge(001) metalorganic molecular beam epitaxial (MOMBE) growth has been performed. It consists of removing the native oxide by ammonia aqueous followed by a diluted sulfuric acid rinse and hydroperoxide treatment to form a passive oxide layer. An extremely uniform surface was obtained by 300 s ammonia etching of the native oxide. Thickness of the oxide layer grown in hydroperoxide is estimated to be approx approx 1.87 nm using angle-resolved X-ray photoelectron spectroscopy measurmeent. A well-ordered 2x1 reflection high-energy electron diffraction pattern appeared after 400 deg C, 30 min annealing in ultra high vacuum. Si_1-x-yGe_xC_y MOMBE growth has been performed on cleaned Ge(001) using disilane (Si_2H_6) and monomethylgermane (CH_6Ge). The (001) axis of the ternary alloy layers is oriented toward Ge(001). No peak corresponding to SiC was detected in X-ray diffraction data. direct C 1997 Elsevier Science S.A. All rights reserved.