Influence of hydrogen on chemical beam epitaxy of GaAs using triethylgallium and diethylarsine

Epitaxial growth of GaAs layers has been studied under very low pressure using organometallic precursors as element sources. These films have been deposited on GaAs(100) in the temperature range 550-650 °C using GaEt3 and AsEt2H. The composition, the structural quality and the growth rate of the layers depend essentially on As:Ga molecular ratio, the deposition temperature and the distance between the injector and the substrate. Without H2 flux, evidence for islanding growth was observed and a high carbon contamination of the layers was revealed by photoluminescence. In presence of molecular hydrogen, a layer-by-layer growth mode occurs and, in addition, carbon incorporation is drastically reduced. Optimal deposition conditions have been determined for this organometallic system in good agreement with a parallel study on in situ analysis of the growth by near-threshold photoemission