QUALITY DEPENDENCE OF PT-N-GAAS SCHOTTKY DIODES ON THE DEFECTS INTRODUCED DURING ELECTRON-BEAM DEPOSITION OF PT

Schottky barrier diodes (SBDs) were fabricated on epitaxially grown n-GaAs by electron beam (e-beam) deposition of Pt at various rates. The quality of the SBDs was evaluated by standard current-voltage (I-V) measurements and the defects introduced during e-beam deposition were characterized by deep level transient spectroscopy (DLTS). The results showed that if the GaAs was shielded from stray electrons originating at the e-beam filament during deposition, then high quality SBDs were formed. However, if the GaAs was not shielded during deposition, then the quality of the devices was poor and the degree to which their characteristics deviated from ideal increased as the deposition rate decreased, i.e., as the total electron dose reaching the substrate during metallization increased. DLTS revealed that several surface and subsurface defects were introduced during metallization without the electron shield and, for the first time, it is shown that these e-beam induced defects result in poor SBD device characteristics.