The major objective of this thesis was to evaluate electrically the damage caused by a
low energy (< 4keV) Ar+ bombardment on n-GaAs(100) surfaces. Electrical measurements
were performed on Schottlky diodes formed on the virgin and the ion-etched surfaces.
The l-V measurements show deterioration of diode parameters by ion etching. The ion etched
diodes have a strong component of surface leakage current. The high frequency
capacitance of ion-etched diodes is less than that of the virgin diodes. The low frequency
capacitance of ion-etched diodes was found to be frequency dispersive. The extent of frequency
dispersion diminishes at low temperatures and at low reverse biases. Virgin diode
capacitance, on the other hand, was found to be independent of frequency.
The electrical characteristics of ion-etched diodes are explained by means of an amorphous
layer and a donor-like damaged layer formed as a result of ion etching. The depth of
the top amorphous layer increases with etch energy. The damaged layer containing the ion
induced traps superimposes over the amorphous layer and extends deep into the bulk semi-conductor. The density of such traps is very bias sensitive and also temperature dependent.
A possible equivalent circuit model for the ion-etched material is proposed. Low temperature
isochronal annealing (< 450°C, 10mins.) was not found effective in causing complete
recovery of the ion-damaged surface.
next to an author's name indicates that all files or directories associated with their ETD are accessible from the Virginia Tech campus network only.
![[VT]](http://scholar.lib.vt.edu/images/ETD-db/restricted.gif)
