Enhanced Photo-Response of Mos2 Photodetectors by a Laterally Aligned SiO2 Nanoribbon Array Substrate

Abstract

Achieving both high photocurrent and small dark current is required for the enhanced performance of molybdenum disulfide (MoS2) photodetector (PD). In the two-dimensional transition metal dichalcogenide PD, inevitable recombinations occur highly at intrinsic defects of MoS2 and impede photo-generated carrier releasement into electrodes, resulting in a poor PD performance. To address this issue without introducing a superiorly high-crystalline MoS2 monolayer and/or complex PD architecture, we for the first time report a facile method of simply transferring the MoS2 onto a periodically aligned silicon dioxide nanoribbons (SNR) array substrate fabricated by 325 nm laser interference lithography. Interestingly, two different n-doping states are arranged alternately on the MoS2 layer, depending on the underlying region of contact substrate (pristine SiO2 and SNR). The different n-doping levels induce internal electric fields by which photo-generated carriers are separated, reducing the recombination chance. The MoS2 PD on the SNR array substrate shows an improved photocurrent to dark current ratio of ∼360 (∼7 times larger than that of the reference PD on the pristine SiO2 substrate), while producing a small dark current of ∼10−12 A at VG=0 V. Our method paves the way for enhancing the performance of other 2D materials-based optoelectronic devices. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim