Metalorganic molecular-beam epitaxy of InGaP

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Abstract
To study the growth mechanism of phosphorus-based III-V ternaries in metalorganic molecular-beam epitaxy, epitaxial growth of In1−xGax P was carried out on GaAs(100) using triethylindium (TEIn), triethylgallium (TEGa), and phosphine under high vacuum (10−5 Torr). Three distinct stages were observed in the temperature dependence of growth rate and Ga composition x of In1−xGax P epilayers. At 390–520 °C, the growth rate and the Ga composition were independent of temperature. The growth rate was proportional to the group-III total flux of TEGa+TEIn, and the Ga composition to the flux ratio of TEGa/(TEGa+TEIn). Lower growth rates were observed with InP-rich compositions below 390 °C, and with GaP-rich compositions above 520 °C. By dividing the growth rate γ into the two growth rates of quasi-binaries [xγ for GaP and (1−x)γ for InP], the pyrolysis of TEGa with an apparent activation energy of 39 kcal/mol was found to limit the growth below 390 °C. At higher temperatures above 520 °C, In droplets were formed on the epilayer surfaces, suggesting that phosphorus evaporation governs the growth. Moreover, a new type of complex defect (InP crystallite partially surrounded by metal In) observed in some cases above 520 °C is reported for the first time.