Single Crystal Epitaxial Germanium Based Ohmic Contact Structure for III-V andNanoelectronic and Mesoscopic Devices

摘要

The single crystal epitaxial layer ohmic contacts are very promising in thefabrication of shallow junction nanoelectronic and mesoscopic devices based on III-V compounds. A single crystal Ge film is grown epitaxially on GaAs or InGaP lattice matched to GaAs and a Au or Pd layer is deposited on top of it using an Ultra High Vacuum (10 to the -9th to 10th powers Torr) Electron Beam (UHV E-Beam) deposition system. The interface between the Ge and thermally cleaned GaAs or InGaP is almost atomically abrupt, smooth and oxide free, and there is a minimum of disruption of the underlying layers. When deposited at an appropriate temperature, the metals are highly oriented and have large grains. They can be diffused through the Ge film to initiate the formation on an ohmic contact in a controlled manner. A detailed analysis of interface quality, crystal structure and defect propagation in GaAs/Ge/Au, GaAs/Ge/Pd, and InGaP/Ge structures is presented. High resolution Transmission Electron Microscopy (HRTEM), Double Crystal X-ray Diffraction (DXRD), Rutherford Backscattering Spectroscopy (RBS) and Auger Electron Spectroscopy (AES) were used to characterize the materials.