VACUUM SUBLIMATION OF GASE - A MOLECULAR SOURCE FOR DEPOSITION OF GASE

The layered structure of GaSe makes it suitable for the technique of V an der Waals epitaxy, a molecular beam deposition technique where hete rostructures are fabricated based on a property of interest and are no t limited by lattice and thermal expansion mismatch. Single crystal Ga Se has been grown on GaAs(111)A by vacuum sublimation from a single Ga Se source without terminating the GaAs surface dangling bonds prior to deposition. Mass spectroscopy was used to determine the composition o f the molecular source. It was found that GaSe sublimates stoichiometr ically to form Ga2Se and Se-2. This results in free selenium (Se-2) in the molecular beam which can terminate the dangling bonds at the GaAs surface prior to bulk GaSe growth. X-ray photoelectron spectroscopy a nd reflection high energy electron diffraction studies of the depositi on confirm this termination process and the structure of subsequent Ga Se growth.