Abstract
Spin injection into a semiconductor is expected to utilize a ferromagnetic material as the electrical contact. One system of potential interest consists of Fe contacts to a GaAs-based device structure. We have used photoreflectance spectroscopy to measure the Schottky barrier height formed for Fe films on GaAs(001) as a function of the GaAs surface reconstruction. The samples were grown by molecular-beam epitaxy in a multichamber UHV facility which includes chambers for photoelectron diffraction and scanning tunneling microscopy. These techniques were used to obtain a detailed atomic model of the Fe/GaAs interface, enabling us to correlate the measured barrier heights with the interfacial structure, and further discuss the results in the framework of several models for Schottky barrier formation. For the As-rich 2×4 and c(4×4) surfaces, we conclude that the interface is formed by Fe bonding with an As monolayer after dissolution of the surface As dimers and some Ga into the Fe film. The samples were removed from the UHV system after coating with 50 Å of Au for the photoreflectance measurements. While the pure Schottky model predicts a value of 0.43 eV, we find nearly identical barrier heights of 0.8 eV for both the 2×4 and c(4×4) surfaces. This is consistent with the similar interfacial structure resulting from Fe growth on each surface, and the value of 0.8 eV is in agreement with that predicted by the effective work function model assuming predominantly Fe–As bonding. We compare these results with similar data for growth on the Ga-rich 4×6 reconstruction and on ZnSe(001) surfaces.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
