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Investigates the dependence of specific contact resistivity of germanium/palladium (Pd)/gallium arsenide (GaAs) and silicon/Pd/GaAs systems in a specific temperature range. Devices based on GaAs and its alloys that require reliable planar low-resistance ohmic contacts; Physical mechanisms responsible for the observed ohmic behavior for the systems; Importance of a heterojunction in forming the ohmic contact.

Deals with a study which investigated the effect of strain-induced band-gap modulation in a GaAs/AlGaAs multiple-quantum-well structure with the wells located at various depths in the structure. Background to the study; Experimental procedures; Results and discussion.

Specific contact resistivity ρc of planar Ge/Pd ohmic contacts to n-type AlxGa1-xAs is measured as a function of AlAs mole fraction x and anneal temperature Tann. The functional dependence of ρc on Tann is the same for all x, decreasing to a minimum at 275–325 °C. This indicates that the ohmic contact formation mechanism is independent of x(0≤x≤0.3) as verified by MeV Rutherford backscattering spectrometry and Read camera glancing angle x-ray diffraction. Decomposition of an epitaxial Pd-AlxGa1-xAs phase is correlated with the onset of ohmic behavior and may result in a thin solid phase regrown interfacial AlxGa1-xAs layer. An undoped 20 nm GaAs cap layer reduces ρc by about one order of magnitude. Ge/Pd contacts display greater dependence of ρc on x and much smoother surface morphology compared with those of standard Au-Ge-Ni contacts on AlxGa1-xAs (0≤x≤0.3). [ABSTRACT FROM AUTHOR]