Morphology-Engineered Optoelectronic Response in CVD-Grown Vertical and Horizontal MoSe 2 Architectures for Efficient Photodetection

Achieving high-sensitivity and fast-response photodetection across a broad spectral range remains a central goal in optoelectronic device engineering. Two-dimensional (2D) materials, particularly transition metal dichalcogenides (TMDs) such as molybdenum diselenide (MoSe 2 ), offer compelling advantages due to their tunable electronic structure, strong light–matter interaction, and compatibility with diverse substrates. Here, we report a morphology-driven photoresponse study of MoSe 2 nanostructures in photoconductor geometry, synthesized via chemical vapor deposition (CVD) techniques in both horizontally (H-MoSe 2 ) and vertically (V-MoSe 2 ) aligned configurations on Si and SiO 2 substrates. Vertically aligned MoSe 2 demonstrated superior photoresponsivity and detectivity and faster response speed compared to its horizontally aligned counterpart due to its larger edge-plane exposure for light absorption and faster charge transfer to the Si substrate. External quantum efficiency (EQE) data reveal that the generated photocurrent of the devices is mostly in the UV–vis absorption region. Again, the V-MoSe 2 devices exhibit higher EQE and photoresponsivity compared to those for H-MoSe 2 -based devices due to the same reason that effectively enhances the detectivity of the device significantly. The V-MoSe 2 /Si device shows peak detectivity of 4.1 × 10 11 Jones at 633 nm with a fast photoresponse speed having rise and decay times of 225 and 186 ms, respectively, which are competitive for photoconductor devices.