Abstract:
Schottky barrier diodes prepared by electron beam deposition (EBD) on Sb-doped n-type Ge
were characterized using deep level transient spectroscopy (DLTS). Pt EBD diodes
manufactured with forming gas in the chamber had two defects, E0.28 and E0.31, which were not
previously observed after EBD. By shielding the samples mechanically during EBD, superior
diodes were produced with no measureable deep levels, establishing that energetic ions created
in the electron beam path were responsible for the majority of defects observed in the unshielded
sample. Ge samples that were first exposed to the conditions of EBD, without metal deposition
(called electron beam exposure herein), introduced a number of new defects not seen after EBD
with only the E-center being common to both processes. Substantial differences were noted
when these DLTS spectra were compared to those obtained using diodes irradiated by MeV
electrons or alpha particles indicating that very different defect creation mechanisms are at play
when too little energy is available to form Frenkel pairs. These observations suggest that when
EBD ions and energetic particles collide with the sample surface, inducing intrinsic
non-localised lattice excitations, they modify defects deeper in the semiconductor thus rendering
them observable.
