Cu, In, and Se were coevaporated onto unheated Mo‐coated substrates of glass and Al2O3. Cu and In partially segregated in these precursors in a direction normal to the film plane. The precursors were annealed in a rapid thermal processor to form CuInSe2(CIS). The films adhered better to the Al2O3than to the glass upon annealing. Solar cells were made by evaporating CdS and top contacts onto the CIS. The best cell had an efficiency of 3.5% and was obtained after annealing the as‐fabricated device in air.