A comparative study was made of rf-sputtered Al on chemically-etched (
CE) and sputter-etched (SE) p-CdTe single crystal surfaces. By means o
f measuring current-voltage, capacitance-voltage and deep level transi
ent spectroscopy (DLTS) characteristics of rf-sputtered A1/p-CdTe Scho
ttky junctions formed on both surfaces, it has been found that surface
preparation techniques can alter the Schottky junction properties. Th
e I-V measurements are seen to closely follow the diode equation of Sc
hottky barrier diodes dominated by thermionic emission. This model is
confirmed by activation energy measurements. Diode factors of about 1.
05 and 1.15, and barrier heights of about 0.63 and 0.75 eV were obtain
ed for C and SE junctions respectively. The dependence of C-2 vs V for
both junctions was found to be almost linear and the slope of the plo
ts yielded a doping density of about 2.6 x 10(15) and 1.2 x 10(15) cm(
-3) for CE and SE junctions respectively. Both junctions show a freque
ncy dispersion at low frequencies which is due to traps in the surface
region. Also deep traps can have effects on the capacitance depending
on trap depth, concentrations and locations. This is exploited in the
DLTS measurements in the temperature range 100-300K, which indicated
the presence of deep trap levels around 0.55 eV above the valence band
for both CE and SE Schottky diodes. Such deep levels are known to inf
luence the electrical properties of II-VI compound semiconductors.