A ballistic electron emission microscopy study of barrier height inhomogeneities introduced in Au/III-V semiconductor Schottky barrier contacts by chemical pretreatments

The distribution of Schottky barrier heights over the contact area in Au/II I-V semiconductor (GaAs, InP, AlxGa1-xAs, InxGa1-xAs) diodes was determined using ballistic electron emission microscopy. Samples which received a che mical pretreatment in aqueous HF or HCl solutions showed changes in the bar rier height distribution. In some cases, shea rinses in deionized water cou ld remove these effects. Additional XPS measurements and our former work on Si enabled us to propose a model wherein negatively charged species contai ning F or Cl at the interface are assumed to be responsible for these chang es in barrier height distribution. However, in some cases, these effects we re shadowed by more drastic influences due to the chemical processing such as changes in the stoichiometry of the surface region.