We made a report on the fabrication and characterization of a mechanically exfoliated multilayered gallium selenide-based metal–semiconductor–metal (MSM) photodetector using Ti/Au as metal contacts. A significant increase in photocurrent was observed when the photodetector was illuminated with a 380 nm laser, giving the photoresponsivity, external quantum efficiency, and detectivity of 2.6 A/W, 850%, and 1.0 × 1012 Jones, respectively, at a power density of 0.35 mW/cm2 at room temperature. Experimentally, it was observed that the device shows high photoresponse in both UV and visible regions. The performance of this GaSe-based photodetector was also checked at various temperatures, ranging from room temperature to 120 °C. It was found that the detector was thermally stable, giving a maximum photoresponsivity of 4.5 A/W at 120 °C.

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Mixed-dimensional heterostructures are emerging to be very promising for the future electronic and optoelectronic applications. Here, we report on the fabrication and characterization of a 2D/3D vertical van der Waals p-n heterojunction based on p-type gallium selenide (GaSe) and n-type gallium oxide (Ga2O3). Kelvin Probe Force Microscopic (KPFM) measurements have been conducted to estimate the difference in the surface potential values between GaSe and Ga2O3, which is further used to find out the conduction band offset value at the GaSe/Ga2O3 hetero-interface to design the band diagrams. The current-voltage measurements on the device display a diode-like behavior which is attributed to the type-II band alignment, present at the p-n junction interface as per the electron affinities and bandgap values of GaSe and Ga2O3. The device exhibits a high current rectification ratio of ~2500 extracted at ± 5 V. The photoresponse properties of the heterostructure are also studied and the figure of merit parameters of the photodetector such as photoresponsivity and specific detectivity have been evaluated for the fabricated device. Since the GaSe/Ga2O3 heterojunction holds a great potential in the field of efficient optoelectronic devices, we believe our study could pave the way to designing innovative optoelectronic devices by integrating low-dimensional materials with conventional 3D semiconducting materials.

We have devised a vertical self-powered GaSe/Si based 2D/3D p–n heterojunction device for a high-performance photodetection application.

Two-dimensional (2D)-layered materials are in prime focus of the researchers because of their excellent optoelectronic properties at the micro- and nanolevels. In this work, we have conducted a comprehensive study on the thickness-dependent optical and optoelectronic properties of the mechanically exfoliated GaSe thin films. Raman and photoluminescence measurements were done on the ultrathin GaSe flakes of different thicknesses to study the change in their phonon modes and optical properties. To understand the optoelectronic properties, metal–semiconductor–metal (MSM) photodetectors were fabricated on GaSe flakes. The performance of the photodetectors was measured in terms of the figure-of-merit parameters of a photodetector such as photoresponsivity (R λ) and external quantum efficiency (EQE). Thicker GaSe flakes provided better performance, with a maximum value of R λ and EQE of ∼0.21 A/W and ∼42, respectively, at 620 nm, as compared to thinner flakes. We believe our study could help to boost the development of future high-performance optoelectronic devices based on quasi-2D materials.