Thin Polycrystalline Films Of Indium Phosphide On Low Cost Substrates Quarterly Report No 1 September 30 1976 January 1 1977

Plans for the six main technical tasks of this 12-month program are discussed and the activities of the first three months are summarized. A new reactor system for growing thin films of InP by the metallorganic-hydride chemical vapor deposition (MO-CVD) process has been completed. Experiments using triethylindium (TEI) and phosphine (PH/sub 3/) reactants in a H/sub 2/ carrier gas have shown that InP films can be successfully grown over a range of deposition temperatures. Epitaxial growth of single-crystal films has been obtained on at least two different crystallographic orientations of single-crystal GaAs at temperatures as low as approximately 525/sup 0/C, and there is evidence that the process can be utilized at even lower temperatures--perhaps below approximately 475/sup 0/C. Films not intentionally doped are n type, with measured carrier concentrations in the 10/sup 16/ cm/sup -3/ range and electron mobilities up to approximately 2000 cm/sup 2//V-sec (room temperature). Initial investigations involve single-crystal substrates (GaAs, sapphire, InP) but various low-cost materials--glasses, alumina ceramics, metals, and certain composites of these--are being selected and evaluated for subsequent use in the program. Specific candidate materials are discussed. The program also involves the formation and evaluation of heterojunction photovoltaic device structures using the InP layers formed by MO-CVD and deposited films of CdS, ZnCdS, and similar II-VI compounds and alloys; this work is done at Stanford University. During the first quarter, two techniques for producing ohmic contacts of Au/Zn/Au on p-type InP were successfully developed, with low contact resistances being achieved following annealing in H/sub 2/ at temperatures up to 475/sup 0/C. Planned work for the next quarter is outlined.