GROWTH OF GAAS AND ALGAAS BY METALORGANIC MOLECULAR-BEAM EPITAXY USING TRIS-DIMETHYLAMINOARSENIC

Due to the extreme toxicity of AsH3, safer alternatives for III-V epitaxy are highly desirable. In addition, the AsH3 Molecule is too stable to decompose on the wafer surface at the temperature and pressure conditions normally used during growth by metalorganic molecular beam epitaxy (MOMBE). This requires the use of high-temperature cracker cells to decompose the AsH3 to elemental As prior to entry to the growth chamber and as a result leads to significant As buildup within the chamber. In this letter we report for the first time MOMBE growth at low temperatures (less-than-or-equal-to 525-degrees-C) using a novel As precursor, tris-dimethylaminoarsenic (DMAAs) without precracking. Specular surface morphologies were obtained over a wide range of growth temperatures, 375-525-degrees-C, for both GaAs and AlGaAs. Carbon concentrations measured by SIMS analysis in GaAs layers deposited from triethylgallium were lower than those obtained using a similar flux of AsH3, while carbon was reduced more than two orders of magnitude in films grown with trimethylgallium and DMAAs as compared to AsH3. No difference in oxygen content was observed between AlGaAs grown with DMAAs and AsH3.