Search

To lower the launch cost and prolong the lifetime of a deep space explorer, solar- and astrophysicists and photonics scientists have devoted much time and energy in exploring and developing a compact and low-power-consumption semiconductor-based vacuum ultraviolet (VUV) photodetector. However, the target has not yet been achieved due to the lack of high external quantum efficiency (EQE) VUV photoconductive materials. Here, we found that two-dimensional MgO, obtained via conformal anneal synthesis method, had ultrasensitive photoresponse to VUV light. It can identify an extremely weak VUV signal (0.85 pW), with a high EQE of 1539%. Such ultrasensitive photoresponse is attributed to the high charge-collection efficiency of excited carriers. Our results provide an idea for developing integrated VUV devices with high responsivity and low power consumption, which will prolong the service time and lower the launch cost of a space explorer.

Electrically responsive plasmonic devices, which benefit from the privilege of surface plasmon excited hot carries, have supported fascinating applications in the visible-light-assisted technologies. The properties of plasmonic devices can be tuned by controlling charge transfer. It can be attained by intentional architecturing of the metal-semiconductor (MS) interfaces. In this study, the wafer-scaled fabrication of two-dimensional (2D) TiO 2 semiconductors on the granular Au metal substrate is achieved using the atomic layer deposition (ALD) technique. The ALD-developed 2D MS heterojunctions exhibited substantial enhancement of the photoresponsivity and demonstrated the improvement of response time for 2D Au-TiO 2 -based plasmonic devices under visible light illumination. To circumvent the undesired dark current in the plasmonic devices, a 2D WO 3 nanofilm (∼0.7 nm) was employed as the intermediate layer on the MS interface to develop the metal-insulator-semiconductor (MIS) 2D heterostructure. As a result, 13.4% improvement of the external quantum efficiency was obtained for fabricated 2D Au-WO 3 -TiO 2 heterojunctions. The impedancometry measurements confirmed the modulation of charge transfer at the 2D MS interface using MIS architectonics. Broadband photoresponsivity from the UV to the visible light region was observed for Au-TiO 2 and Au-WO 3 -TiO 2 heterostructures, whereas near-infrared responsivity was not observed. Consequently, considering the versatile nature of the ALD technique, this approach can facilitate the architecturing and design of novel 2D MS and MIS heterojunctions for efficient plasmonic devices.