Ultraviolet Photodetectors and Field‐Effect Transistors Based on β‐Ga ₂ O ₃ Nanomembranes Produced by Ion‐Beam‐Assisted Exfoliation

β‐Ga 2 O 3 nanomembranes obtained by ion‐beam‐assisted exfoliation are used in the fabrication of simple metal–semiconductor–metal (MSM) structures, that are tested as photodetectors (PD) and field‐effect transistors (FET). Ti/Au contacts to the membrane are found to be rectifying. However, through thermal treatment in a nitrogen atmosphere for one minute at 500 °C, it is possible to modify this junction to have an ohmic behavior. An MSM PD is studied, reaching a high responsivity of 2.6 × 10 4 A W −1 and a detectivity of 2.4 × 10 14 Jones, under 245 nm wavelength illumination, and an applied voltage of 40 V. To better understand the behavior of the two junctions, in particular the iono/photocurrent mechanisms, an ion microprobe system is used to assess the response of these PD when excitation is localized in the different regions of the device. Finally, a depletion‐mode FET is obtained, with an ON/OFF current ratio of 7.7 × 10 7 in the linear regime, at a drain‐to‐source voltage of 5 V, and with a threshold voltage around −3 V. The success in obtaining FET, and most notably, MSM PD, while using a simple device structure, indicates a great potential of the nanomembranes produced by ion‐beam‐assisted exfoliation for the development of high‐performance devices.