In-Situ $I\hbox{--}V$ Measurements of ${\rm ZnS}{:}{\rm TiO}_{2}/{\rm p}\hbox{-}{\rm Si}$ Quantum Dot Heterojunction Photodiode Under 120 MeV ${\rm Au}^{9+}$ Ion Irradiation

The 120 MeV
${\rm Au}^{9+}$
ion induced modifications in a
${\rm ZnS}{:}{\rm TiO}_{2}/{\rm p}\hbox{-}{\rm Si}$
quantum dot (QD) heterojunction has been studied by In-Situ current-voltage
$(I\hbox{--}V)$
measurements. This paper shows that the process of ion irradiation is a novel technique in modifying the electronic properties of QDs based semiconductor heterojunctions. After
${\rm Au}^{9+}$
ion irradiation, there is an increase in ideality factor for
${\rm ZnS}{:}{\rm TiO}_{2}/{\rm p}\hbox{-}{\rm Si}$
QDs heterojunction at lower fluences and further at higher fluences the ideality factor decreases. In addition, the other parameters like leakage current, series resistance, and reverse saturation current are also affected under the SHI irradiation. In pristine samples, the dependence of the currents under the light illumination shows high photo responsivity. The observed responsivity is
$2.7\times 10^{10}~{\rm A}/{\rm W}$
for ultraviolet light (wavelength 376 nm) at reverse bias voltage 1.5 V. The increase in responsivity to
$4.9\times 10^{10}~{\rm A}/{\rm W}$
is observed after irradiation up to fluence of
$3\times 10^{13}~{\rm ions}/{\rm cm}^{2}$
.