Color-selective photodetection from intermediate colloidal quantum dots buried in amorphous-oxide semiconductors

Kyung-Sang Cho,Heejeong Jeong,Sungwoo Hwang,Sang Yeol Lee,Jun Young Choi,Chan-Wook Baik,Keun Heo

doi:10.1038/s41467-017-00893-x

Abstract

We report color-selective photodetection from intermediate, monolayered, quantum dots buried in between amorphous-oxide semiconductors. The proposed active channel in phototransistors is a hybrid configuration of oxide-quantum dot-oxide layers, where the gate-tunable electrical property of silicon-doped, indium-zinc-oxide layers is incorporated with the color-selective properties of quantum dots. A remarkably high detectivity (8.1 × 1013 Jones) is obtained, along with three major findings: fast charge separation in monolayered quantum dots; efficient charge transport through high-mobility oxide layers (20 cm2 V−1 s−1); and gate-tunable drain-current modulation. Particularly, the fast charge separation rate of 3.3 ns−1 measured with time-resolved photoluminescence is attributed to the intermediate quantum dots buried in oxide layers. These results facilitate the realization of efficient color-selective detection exhibiting a photoconductive gain of 107, obtained using a room-temperature deposition of oxide layers and a solution process of quantum dots. This work offers promising opportunities in emerging applications for color detection with sensitivity, transparency, and flexibility.

Highlights

We report color-selective photodetection from intermediate, monolayered, quantum dots buried in between amorphous-oxide semiconductors
We measured the mobilities of the OQO films for R, G, and B quantum dots (QDs) buried in the SIZO layers and for different QD layer thicknesses, along with that of a 40-nm SIZO layer without QDs
We demonstrated ultrasensitive photodetection using monolayered QDs buried in amorphous-oxide SIZO phototransistors

Summary

Introduction

We report color-selective photodetection from intermediate, monolayered, quantum dots buried in between amorphous-oxide semiconductors. The fast charge separation rate of 3.3 ns−1 measured with time-resolved photoluminescence is attributed to the intermediate quantum dots buried in oxide layers These results facilitate the realization of efficient color-selective detection exhibiting a photoconductive gain of 107, obtained using a room-temperature deposition of oxide layers and a solution process of quantum dots. A strong demand for complementary metal-oxide semiconductor (CMOS)-compatible, monolithic integration with a low-cost and simple fabrication process has arisen, which may not be achievable using epitaxially grown III–V semiconductors for photoconductors, avalanche photodiodes, and photomultipliers Such devices have disadvantages related to material growth conditions, high-voltage operation, and bulkiness, including increased fabrication cost and complexity. Colloidal quantum dots (QDs), often referred to as semiconductor nanocrystals, are processible for integration onto various substrates using a low-cost, solutioncoating method They have unique optical properties, such as bandgap energies tunable by adjusting their sizes, narrow emission bandwidths, broad absorption spectrum, and high photoluminescence quantum efficiencies. Interface control between QDs and graphene remains an issue[2, 17]

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Conclusion