Contamination-free assembly of two-dimensional van der Waals heterostructures toward high-performance electronics and optoelectronics

• A novel vdW-transfer technique enables contamination-free assembly of 2D crystal devices. • The vdW-assisted layer is universal, improving device performance across various 2D crystals. • MoS 2 /WSe 2 photodetectors show 5.7-fold responsivity enhancement using vdW-transfer. • WSe 2 -FETs fabricated via vdW-transfer exhibit a 30-fold increase in hole mobility, an order-of-magnitude reduction in hysteresis, and a 4-fold reduction in subthreshold swing. Mechanical exfoliation and transfer of two-dimensional (2D) crystals are usually used to fabricate van der Waals (vdW) heterostructural electronic and optoelectronic devices for fundamental studies. However, the conventional transfer (c-transfer) techniques often involve direct contact between the polymer supports and the 2D crystals, resulting in surface contamination that degrades device performance. Here, we present a novel vdW-transfer technique utilizing a polyvinyl chloride-covered polydimethylsiloxane microdome polymer (MDP) with a vdW-assisted layer, enabling a contamination-free assembling of 2D crystal-based electronic and optoelectronic devices. This vdW-assisted layer prevents direct contact between the polymer and target materials, yielding high-quality interfaces free of interlayer contamination and enhancing device performance. Using this vdW-transfer technique, we fabricate MoS 2 /WSe 2 heterostructure photodetectors and WSe 2 field-effect transistors (FETs). Compared with the photodetector fabricated by the c-transfer technique, the device fabricated by the vdW-transfer method exhibits a significant improvement in the linearity (from 0.61 to 1.01) of photoresponse, a 5.7-fold enhancement in responsivity, and an order-of-magnitude decrease in response time. Additionally, the WSe 2 -FET produced by the vdW-transfer demonstrates nearly a 30-fold increase in hole carrier mobility, an order-of-magnitude reduction in hysteresis, and a 4-fold reduction in subthreshold swing compared with FET fabricated by the c-transfer method. We introduce a universal van der Waals (vdW) transfer technique using a microdome polymer with a vdW-assisted layer, enabling contamination-free assembly of 2D crystal devices. This method significantly enhances device performance, yielding high-quality MoS 2 /WSe 2 photodetectors and WSe 2 field-effect transistors with superior responsivity, mobility, and stability.