Cadmium sulfide nanocrystal sensitized vertically aligned titanium dioxide rods for large area image sensors on 3-D substrates

Abstract

We discuss here a semiconductors assembly comprising of titanium dioxide (TiO₂) rods sensitized by cadmium sulfide (CdS) nanocrystals for potential applications in large area electronics on three dimensional (3-D) substrates. Vertically aligned TiO₂ rods are grown on a substrate using a 150° C process flow and then sensitized with CdS by SILAR method at room temperature. This structure forms an effective photoconductor as the photo-generated electrons are rapidly removed from the CdS via the TiO₂ thereby permitting a hole rich CdS. Current-voltage characteristics are measured and models illustrate space charge limited photo-current as the mechanism of charge transport at moderate voltage bias. The stable assembly and high speed are achieved. The frequency response with a loading of 10 pF and 9 MΩ shows a half power frequency of 100 Hz.