Microstructural Characterization of Ohmic Contacts to InGaAs Capping Layers

摘要

microstructural characterization of the annealingbehaviour of two ohmic contact metallizations, Ti/Pt/Au andMo/Au, to InCaAs/InP has been carried out using transmissionelectron microscopy (TEM). Both metallization schemes weredeposited sequentially by electron beam evaporation onto highly p-type doped (1-2x10~19cm~-3) InCaAs epitaxial layers, grown on<100> InP. Wafers were sectioned and annealed at temperaturesranging from 200-500 deg C. Mo/Au contacts exhibited betteroverall thermal stability; interdiffusion and reactions weresuppressed up to approx = 425 deg C, whereupon Au diffusedthrough the Mo layer to react with InCaAs, resulting in Au_9In_4and MoAs formation. Ti/Pt/Au contacts, on the other hand, reactedwith InCaAs at temperatures as low as 275 deg C, with In and TiAsforming at the Ti/InCaAs interface.