In Situ I - V Measurements of an Ultraviolet Enhanced $\hbox{ZnS:TiO}_{2}/\hbox{n-Si}$ Quantum Dot Heterojunction Photodiode Under 120 MeV $\hbox{Au}^{9+}$ Ions

This paper reports the development of a
$\hbox{ZnS:TiO}_{2}/\break \hbox{n-Si}$
heterojunction photodiode structure by deposition of colloidal
$\hbox{ZnS:TiO}_{2}$
quantum dots (QDs) on the n-Si substrate. To study the diode performance under harsh radiation atmospheres, in situ dark
$I$
–
$V$
characteristics of the
$\hbox{ZnS:TiO}_{2}/\hbox{n-Si}$
photodiode have been studied under the irradiation of 120 MeV
$\hbox{Au}^{9+}$
ions with an incremental increase in fluences from
$\hbox{3} \times \hbox{10}^{11}$
to
$\hbox{1} \times \hbox{10}^{13} \ \hbox{ions/cm}^{2}$
. It shows the increase in rectification behavior with the increase in irradiation fluences caused by interface smoothening and interface defect annealing at higher fluences. X-ray diffraction patterns and TEM analysis also show the increased crystallinity of
$ \hbox{ZnS:TiO}_{2}$
QDs of size approximately 2–5 nm, whereas photoluminescence spectra show the reduction of defects. These results are in support of the irradiation-induced effects in in situ
$I$
–
$V$
measurements. The studies are also made for ultraviolet light of 376 nm wavelength (laser power 50 mW) and visible light of power 60 W for pristine and irradiated (at fluence
$\hbox{1} \times \hbox{10}^{13} \ \hbox{ions/cm}^{2}$
)
$\hbox{ZnS:TiO}_{2}/\hbox{n-Si}$
heterojunction photodiodes.