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

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 V_G=0 V. Our method paves the way for enhancing the performance of other 2D materials-based optoelectronic devices.