am501481w_si_001.pdf (2.16 MB)
Enhanced Photocurrent and Dynamic Response in Vertically Aligned In2S3/Ag Core/Shell Nanorod Array Photoconductive Devices
journal contribution
posted on 2014-06-11, 00:00 authored by Hilal Cansizoglu, Mehmet
F. Cansizoglu, Fumiya Watanabe, Tansel KarabacakEnhanced photocurrent values were
achieved through a semiconductor-core/metal-shell nanorod array photoconductive
device geometry. Vertically aligned indium sulfide (In2S3) nanorods were formed as the core by using glancing
angle deposition technique (GLAD). A thin silver (Ag) layer is conformally
coated around nanorods as the metallic shell through a high pressure
sputter deposition method. This was followed by capping the nanorods
with a metallic blanket layer of Ag film by utilizing a new small
angle deposition technique combined with GLAD. Radial interface that
was formed by the core/shell geometry provided an efficient charge
carrier collection by shortening carrier transit times, which led
to a superior photocurrent and gain. Thin metal shells around nanorods
acted as a passivation layer to decrease surface states that cause
prolonged carrier lifetimes and slow recovery of the photocurrent
in nanorods. A combination of efficient carrier collection with surface
passivation resulted in enhanced photocurrent and dynamic response
at the same time in one device structure. In2S3 nanorod devices without the metal shell and with relatively thicker
metal shell were also fabricated and characterized for comparison.
In2S3 nanorods with thin metal shell showed
the highest photosensitivity (photocurrent/dark current) response
compared to two other designs. Microstructural, morphological, and
electronic properties of the core/shell nanorods were used to explain
the results observed.