Influence of the electron beam evaporation rate of Pt and the semiconductor carrier density on the characteristics of Pt/nhyphen;GaAs Schottky contacts

摘要

Schottky barrier diodes (SBDs) were fabricated on epitaxially grownnhyphen;GaAs materials, with different free carrier densities, by electron beam (ehyphen;beam) evaporation of Pt at various rates. The quality of the SBDs was evaluated by standard currenthyphen;voltage (Ihyphen;V) measurements, while the defects introduced duringehyphen;beam evaporation were characterized by deep level transient spectroscopy (DLTS). The results showed that if the GaAs was shielded during Pt deposition from stray electrons originating at theehyphen;beam filament, high quality SBDs were formed. However, if the GaAs was not shielded during deposition, the quality of the diodes was poor and the degree to which their characteristics deviated from the ideal case increased as the total electron dose reaching the substrate increased (for slow evaporation rates) and as the free carrier density of the GaAs increased. DLTS revealed that several surface and subsurface defects were introduced during metallization without the electron shield and it is shown that these defects are responsible for the poor device quality. The nature of some of these defects depended on the free carrier density of the GaAs.