Film growth and reaction kinetics studies have shown that trigermane (Ge 3H 8) is a superior Ge source for the epitaxial synthesis of Ge 1-ySn y/Si(100) alloys using ultra-high vacuum chemical vapor deposition. The Ge 3H 8/SnD 4 combination yields 3-4 times higher growth rates than the traditional Ge 2H 6/SnD 4 approach, with film Sn/Ge ratios reflecting the corresponding gas-phase stoichiometries much more closely. These advances have led to optical quality Ge 1-ySn y layers with Sn concentrations up to at least 9 and thicknesses approaching 1 μm. These thick films are found to be crucial for the observation of a strong, tunable photoluminescence signal near the threshold of the predicted direct-indirect bandgap crossover.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)