In-situ conductance characterization of Fe/Ag multilayer contacts on GaAs
Dustin Hite, Stephen E. Russek, David P. Pappas
Electrical transport characteristics for epitaxially grown Ag/Fe/Ag multilayers on GaAs(100) and GaAs(110) have been studied under various growth conditions. The surfaces and structure of the multilayer were characterized by low energy electron diffraction and angle-resolved Auger electron spectroscopy/diffraction at all stages of the growth. In-situ conductance spectroscopy performed between growth steps indicates a strong dependence on the morphology at the metal/semiconductor interface. A nanoclustered Ag overlayer exhibits a reverse current due to defect states in the discontinuous film; however, annealed, continuous Ag overlayers on GaAs behave as a uniform rectifying diode. After completion of the magnetic multilayer growth, current-voltage characteristics indicate a sharp turn-on in the reverse current at 0.6 V with non-linear behavior. This is characteristic of electron tunneling through the Schottky barrier from the multilayer contact into the semiconductor. The implementation of these magnetic multilayer contacts for electrical spin injection is discussed.