CONTROL OF GAAS SCHOTTKY-BARRIER HEIGHT BY ULTRATHIN MOLECULAR-BEAM EPITAXY SI INTERFACE CONTROL LAYER

An attempt is made to control the Schottky barrier height (SBH) of Al/GaAs(100) Schottky barrier diodes by inserting an ultrathin Molecular beam epitaxy (MBE) Si interface control layer (Si ICL). A theory for SBH control including an ideal case and a relaxed case is presented based on the disorder-induced gap state (DIGS) model. The Schottky barrier height (SBH) is measured by the X-ray photoelectron spectroscopy (XPS), current-voltage (I-V) and capacitance-voltage (C-V) techniques. Theory and experiment show that the SBH can be varied precisely over a wide range of about 400 meV by the use of pseudomorphic Si ICL with suitable As doping. When the Si ICL is above the critical thickness of 10 A, SBH control becomes more difficult due to competition between the ionized dopant atoms and the ionized interface states at the Si ICL-GaAs interface.