Flexible and Wavelength-Selective MoS2 Phototransistors with Monolithically Integrated Transmission Color Filters

Geonwook Yoo,Sol Lea Choi,Min Suk Oh,Sang Jin Park,Hui Joon Park,Junseok Heo,Sanghyun Lee,Kyu-Tae Lee

doi:10.1038/srep40945

Abstract

Color-selective or wavelength-tunable capability is a crucial feature for two-dimensional (2-D) semiconducting material-based image sensor applications. Here, we report on flexible and wavelength-selective molybdenum disulfide (MoS2) phototransistors using monolithically integrated transmission Fabry-Perot (F-P) cavity filters. The fabricated multilayer MoS2 phototransistors on a polyarylate substrate exhibit decent electrical characteristics (μFE > 64.4 cm2/Vs, on/off ratio > 106), and the integrated F-P filters, being able to cover whole visible spectrum, successfully modulate the spectral response characteristics of MoS2 phototransistors from ~495 nm (blue) to ~590 nm (amber). Furthermore, power dependence of both responsivity and specific detectivity shows similar trend with other reports, dominated by the photogating effect. When combined with large-area monolayer MoS2 for optical property enhancement and array processing, our results can be further developed into ultra-thin flexible photodetectors for wearables, conformable image sensor, and other optoelectronic applications.

Highlights

We present flexible and wavelength-selective MoS2 phototransistors using monolithically integrated transmission Fabry-Perot (F-P) cavity filters, which can modulate its spectral response from blue (~495 nm) to amber (~590 nm) color
SU-8 was spin-coated with a target thickness of about 2.5 um for optical separation of MoS2 phototransistor from the F-P cavity, followed by S/D contact opening using exposure and develop process
F-P cavity structures were fabricated by sequentially depositing Ag, SiO2 and Ag on SU-8 layer using e-beam evaporator, and S/D contacts were opened again using conventional lithography and wet etching process

Summary

Introduction

We present flexible and wavelength-selective MoS2 phototransistors using monolithically integrated transmission Fabry-Perot (F-P) cavity filters, which can modulate its spectral response from blue (~495 nm) to amber (~590 nm) color. We designed and integrated the F-P cavity color-filters based on a metal-insulator-metal (MIM) structure[31,32,33,34,35], instead of traditional organic dye-based filters that are susceptible to environment and difficult for making ultra-thin structure[36,37]. Electrical characteristics before and after the F-P cavity integration. Spectral response characteristics as well as other figure-of-merits (e.g. responsivity, specific detectivity) of the integrated MoS2 phototransistors are investigated and discussed. The results unveil the potential of MoS2 phototransistors integrated with thin F-P cavity color filters for applications in flexible and non-planar image sensors

Methods

Results

Conclusion