Abstract:
A process and apparatus for producing thick films of a material, containing a number of constituents such as compounds, physical mixtures and alloys of material, by flash evaporation is described. Specifically, high feed rates of the material, gallium arsenide, for example, to be flash evaporated are required for depositing uniform, thick films on a substrate and such high feed rates are made possible by preventing clogging of the feed apparatus by the feed materials. Clogging is prevented by the use of a guide funnel and guide tube arrangement which are disposed one above the other in coaxial vertical alignment with an aperture in a box source heater, the lower extremity of the guide tube is vertically displaced from the aperture a distance sufficient to maintain the temperature of the guide tube below the decomposition or melting temperature of the material but at a temperature in excess of the condensation temperature of the more volatile constituent of the material being evaporated; arsenic in the instance where gallium arsenide is being evaporated.