Planar reactive evaporation apparatus for the deposition of compound semiconducting films

A planar source cavity for use in a vacuum deposition chamber at temperatures in excess of 300.degree. C. where pressures less than 10.sup.-8 torr are created to facilitate the preparation of heteroepitaxial compound semiconductor films onto single crystal substrates comprising an inert cylindrically shaped dish mounted onto non-conducting spacers joining said dish to an electrical heating means and providing electrical insulation from said heating means, an inlet line extending through the bottom of said dish to a means for controlling the flow of gaseous material into said dish, and a perforated top mounted on the top of said dish thereby forming an enclosed cavity which facilitates the control of gaseous vapor pressures created within said dish and directs the flow of said gaseous vapors from said dish in a direction perpendicular to said top when said source cavity is enclosed in said deposition chamber.