Large-area synthesis of 2D MoO 3− x for enhanced optoelectronic applications

Two-dimensional (2D) molybdenum trioxide has been attracting research interest due to its bandgap tunability and a wide variety of desirable electronic/optoelectronic properties. However, the lack of a reproducible synthesis process for obtaining large coverage 2D MoO3 has limited the use of this material. Here we report the synthesis of large area 2D MoO3−x via physical vapor deposition, using MoO3 powder as the precursor. The as-grown layers are directly deposited on SiO2/Si, eliminating the necessity for any transfer process. These as-grown MoO3−x layers allow for the large-scale fabrication of planar device arrays. The applicability of 2D MoO3−x in optoelectronics is established via the demonstration of low-power ultraviolet (UV) sensor arrays, with rapid response times (200 µs) and responsivity up to 54.4 A · W−1. At a bias voltage of 0.1 V, they are at least 400 times more power efficient than their next best contender.