Single Crystal Epitaxial Ge Based Contacts to Gaas, and InGap

Abstract

ABSTRACTNonalloyed, single crystal, oxide free Ge based ohmic contacts are almost atomically abrupt, have a smooth interface, and have the potential to be better understood. Ultra high vacuum electron beam evaporation is used to deposit a single crystal Ge film on GaAs and InGaP substrates. A large grain, highly oriented Au film or a poly crystalline Pd film with more randomly oriented grains was then deposited on the Ge. These films were characterized in the as grown condition by high resolution electron microscopy (HREM), double crystal x-ray diffraction (DXRD), Auger electron spectroscopy (AES), Rutherford back scattering (RBS) and scanning electron microscopy (SEM). The as deposited Ge film grown at 400°C on GaAs and at 350°C on InGaP are epitaxial with a smooth abrupt, oxide free interface. The highly oriented Au film deposited at 100°C had a smooth interface with the Ge with the orientation relationship (100)Au II (100)Ge and [001]Au II [011 ]Ge or [0-1 1 ]Ge.