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 us ing organometallic precursors as element sources. These films have been dep osited on GaAs(100) in the temperature range 550-650 degreesC using GaEt3 a nd AsEt2H. The composition, the structural quality and the growth rate of t he layers depend essentially on As:Ga molecular ratio, the deposition tempe rature and the distance between the injector and the substrate. Without H-2 flux, evidence for islanding growth was observed and a high carbon contami nation of the layers was revealed by photoluminescence. In presence of mole cular hydrogen, a layer-by-layer growth mode occurs and, in addition, carbo n incorporation is drastically reduced. Optimal deposition conditions have been determined for this organometallic system in good agreement with a par allel study on in situ analysis of the growth by near-threshold photoemissi on.