The objective of this proposal is directed toward the formation of non-spiking ohmic contacts to p-type InP. It is proposed here to apply the principle of solid phase regrowth (SPR) to fabricate such contacts to p-InP. Shallow contacts (reaction depth<100A) of mid 107n- cm2 contact resistivity have been achieved on n- and p-type GaAs by the SPR method. The regrowth process begins with a low-temperature reaction between a metal M (e.g. Pd or Ni) and a compound semiconductor substrate, AB, to produce an intermediate ternary MxABy phase. A subsequent reaction at a higher temperature between an overlayer of Si, Ge, or In and the intermediate phase results in the decomposition of the intermediate phase and the epitaxial regrowth of a layer of the compound semiconductor doped or alloyed with the overlayer element. The nonstoichiometry of the intermediate ternary MxABy phase (i.e. where y is not equal to 1) will allow the doping element to occupy the preferential sites (site selection mechanism), thus forming a highly doped surface regrown layer. A thin layer of doping element (i.e. Mg, Mn, Si, or Ge) imbedded in metal M has been used to successfully intentionally dope the regrowth layer to reduce the contact resistivity significantly. In this project, the Pd- and Ni-based contact system will be investigated since ternary compounds such as Pd4.8InP and Ni2.7InP have been observed between Pd, Ni and InP at low temperatures. Overlayers of Ge, Si, In or Sb will be investigated to drive the decomposition of the Pd (or Ni) ternary compounds and the epitaxial regrowth of Inp. The effects of a thin layer of embedded acceptor element on the electrical characteristics (i.e. Mn, Mg, or Zn) will be carried out. In this research cross-sectional transmission electron microscopy and backside secondary ion mass spectrometry will be used for structural investigation, and Transmission Line Model measurements will be utilized for electrical measurement. The SPR contacts are expected to provide more uniform interfaces and lower contact resistivity compared to.
