Strain Engineering in Monolayer Graphene via ZnO Array Substrates in Schottky Junction for Enhanced Optoelectronic Performance

Strain engineering has emerged as a powerful technique for modulating the bandgap in two-dimensional (2D) materials, including transition metal dichalcogenides (TMDCs) and graphene, which are critical for structural optimization in nanoelectronics and optoelectronics. Despite the promise of these materials, a significant challenge remains in achieving precise and controllable strain effects, particularly in graphene, to exploit its full potential in device applications. This gap in controllability limits the ability to fully leverage the sensitive changes in interfacial properties that strain can induce in 2D materials. Here, we present an approach to precisely control strain effects in monolayer graphene by applying mechanical force through a ZnO array substrate. The ZnO arrays were fabricated with controlled dimensions using lithographic templates, allowing for accurate strain modulation when graphene was wet-transferred onto the array. This method enabled effective coupling between the strain in graphene and the graphene/ZnO Schottky junction, significantly enhancing the device's optoelectronic performance. The resulting device demonstrated a broad response from ultraviolet to visible spectrum. Remarkably, the device achieved an outstanding responsivity of 39.1 mA W⁻¹ at 320 nm with a 3V bias. These findings provide a practical and innovative solution to the challenges of strain engineering in 2D materials.