FORMATION MECHANISM OF SCHOTTKY BARRIERS ON MBE-GROWN GAAS-SURFACES SUBJECTED TO VARIOUS TREATMENTS

Al, Mg and Au Schottky barriers were formed on MBE-grown GaAs(100) surfaces subjected to various treatments including chemical etching, ion etching, sulfur treatment and insertion of an ultrathin Si interface control layer (Si-ICL). There were characterized by the X-ray photoelectron spectroscopy (XPS), current-voltage (I-V) and capacitance-voltage (C-V) techniques. The XPS results indicated the presence of an interfacial layer (IL) in each case. Although the behavior is far from the ideal Schottky limit, the barrier height showed dependences on the properties of ILs and the metal work-function. Based on the disorder-induced gap state (DIGS) model, a theory including the effect of an insulator-like or semiconductor-like IL was developed. The theory explains the observed behavior reasonably well, showing that the detailed nature of the IL is the key feature for the understanding and control of Schottky barriers.