The observation of an antisymmetric magnetoresistance in a trilayer van der Waals heterostructure Fe ₃ GeTe ₂ /graphite/Fe ₃ GeTe ₂ .

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 MoO ₃ has limited the use of this material. Here we report the synthesis of large area 2D MoO _{3− x} via physical vapor deposition, using MoO ₃ powder as the precursor. The as-grown layers are directly deposited on SiO ₂ /Si, eliminating the necessity for any transfer process. These as-grown MoO _{3− x} layers allow for the large-scale fabrication of planar device arrays. The applicability of 2D MoO _{3− x} in optoelectronics is established via the demonstration of low-power ultraviolet (UV) sensor arrays, with rapid response times (200 µ s) 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.