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Integration of nanolayered metal chalcogenides with wide-bandgap semiconductors forming pn heterojunction leads to the way of high-performance photodetection. This work demonstrates the fabrication of a few nanometer thick Molybdenum diselenide (MoSe2)/Mg-doped Gallium Nitride (p-GaN) heterostructure for light detection purposes. The device exhibits low noise broadband spectral response from ultraviolet to near-infrared range (300â€"950 nm). The band-alignment and the charge transfer at the MoSe2/p-GaN interface promote self-powered photodetection with high photocurrent to dark current ratio of 2000 and 1000 at 365 nm and 640 nm, respectively. A high responsivity of 130 A Wâˆ'1, detectivity of 4.8 × 1010 Jones, and low noise equivalent power of 18 fW/Hz1/2 at 365 nm is achieved at an applied bias of 1 V. Moreover, the transient measurements reveal a fast rise/fall time of 407/710 ÎĽ sec for the fabricated device. These outcomes exemplify the viability of MoSe2/p-GaN heterostructure for high-speed and low-noise broadband photodetector applications. [ABSTRACT FROM AUTHOR]

Heterojunction photodiodes comprising of layered metal chalcogenides and wide‐bandgap semiconductors are a promising candidate for broadband photodetection. In this work, nanolayered Molybdenum diselenide (MoSe2)/Gallium Nitride (GaN) based photodetector has been demonstrated from ultraviolet to near‐infrared range (300–1000 nm). The performance is investigated by conducting Kelvin probe force microscopy to measure the conduction band offset at the interface of the heterojunction. It is used to analyze the energy‐band diagrams to understand the current transport mechanism. The device exhibits a high photoconductive gain of 1.8 × 104, responsivity of 5580 A W−1, detectivity of 1.9 × 1011 Jones and low noise equivalent power of 10 fW Hz−1/2 at 365 nm. Additionally, finite difference time domain simulations are performed for the MoSe2/n‐GaN heterostructure to authenticate the broadband photodetection spectrum. Therefore, the outcomes of this study validate the suitability of MoSe2/n‐GaN heterojunction devices for high responsivity and detectivity applications. [ABSTRACT FROM AUTHOR]

Here, an optically pumped terahertz (THz) modulator based on the novel transition metal dichalcogenide (TMD) material platinum diselenide (PtSe2) is demonstrated. The nanostructured PtSe2 thin films are formed by direct selenization of the sputtered platinum film on a high‐resistivity silicon substrate. Raman spectroscopy, scanning electron microscopy, and high‐resolution transmission electron microscopy confirm the formation of polycrystalline PtSe2 nanostructures. The transmission measurements reveal the modulation of the THz waves in the wide frequency range of 0.1–1 THz. The modulation depth of 32.7% is achieved under low pumping laser power of 1 W cm−2. The numerical analysis based on the finite difference time domain method is in good agreement with the experimentally obtained results. Further, the simulation results manifest that higher modulation depth can be achieved with the utilization of higher laser power. This work provides a path for the application of TMD materials like PtSe2 in the development of THz tunable devices such as modulators, polarizers, filters. [ABSTRACT FROM AUTHOR]