GaAs films grown by vacuum chemical epitaxy using thermally precracked trimethyl-arsenic

Abstract

Trimethyl-arsenic (TMAs) is used as a source of arsenic for GaAs film growth. In the process used, vacuum chemical epitaxy, TMAs is thermally decomposed into arsenic upstream in a hot cracker furnace. The arsenic and stable hydrocarbons are then transported in vacuum without condensation to the epitaxial growth zone. The hole carrier concentration and carbon content in grown films are studied via Hall, electrochemical profile, and secondary ion mass spectroscopy as a function of cracker furnace design. It is shown that when the TMAs decomposition efficiency is poor, the carbon content can be as high as 1019/cm3 but for a more efficient cracker, the carbon content can be reduced into the 1016/cm3 range. Toxic injury hazards can be reduced substantially by substituting TMAs for the more widely used arsine in GaAs growth systems.