Raman Spectroscopy Reveals New 2D Semiconductor Material Showing Promise for UV-Visible Light Detection

As the demand for highly sensitive photodetectors grows, researchers continue to explore novel two-dimensional (2D) materials that can enhance device performance (1,2). In a recent study published in the Chinese Journal of Physics, a team of scientists from Southern Taiwan University of Science and Technology and National Cheng Kung University have demonstrated the potential of HgPSe₃ thin flakes for UV-Vis photodetection. The research, conducted by Yung-Lan Chuang, Yu-Tsun Yao, Bo-Cheng Yang, Chin-Shan Lue, Chia-Nung Kuo, Ming-Lun Lee, and Jinn-Kong Sheu, provides crucial insights into the material’s Raman spectral properties and photodetection capabilities (1).

Mercury phosphorus selenide (HgPSe₃) is a layered semiconductor material, metal phosphorus trichalcogenide (MPT) compound, belonging to a family of two-dimensional (2D) materials that have recently gained attention for their unique optical and electronic properties (1,2).

Raman Spectroscopy Highlights Structural Uniformity

Raman spectroscopy is a vital tool for characterizing the optical and vibrational properties of 2D materials. The researchers investigated the Raman spectra of HgPSe₃ thin flakes and bulk samples using excitation lasers at 532 nm and 633 nm. Their results revealed two dominant Raman peaks at 147.8 cm⁻¹ and 213.9 cm⁻¹, indicating that flake thickness has little effect on the Raman spectra. This suggests a high degree of structural integrity and uniformity, making HgPSe₃ a stable candidate for optoelectronic applications (1).

The use of multiple excitation wavelengths allowed the researchers to assess how layer thickness influences spectral characteristics. Notably, the 633 nm laser provided better discrimination between different flake thicknesses at lower power densities compared to the 532 nm laser, offering a refined method for analyzing HgPSe₃ structural properties (1).

HgPSe₃ Thin Flakes as Photodetectors

Beyond Raman analysis, the study explored the application of HgPSe₃ thin flakes in photodetectors. The researchers fabricated photodetectors using mechanically exfoliated HgPSe₃ thin films deposited onto a sapphire substrate. Metal-semiconductor-metal (MSM) photodetectors were created by incorporating Ni/Au metal contacts, enabling efficient electrical performance (1).

The HgPSe₃-based photodetectors demonstrated exceptional performance, particularly in terms of their low dark current, which was measured in the femtoampere range. This ultra-low noise level is crucial for high-sensitivity detection applications. The devices exhibited a spectral response from 400 nm to 630 nm, with a sharp cutoff around 590 nm, corresponding to an estimated bandgap of approximately 2.1 eV (1).

Fast Response Times and Potential Applications

One of the key highlights of this study is the photodetector’s fast response time. Under an applied bias voltage of 5 V and an illumination wavelength of 500 nm, the devices achieved a response time of approximately 28 milliseconds. This rapid reaction makes HgPSe₃ an attractive material for real-time photodetection applications, including environmental monitoring, biomedical imaging, and optical communication (1).

The high sensitivity and stability of HgPSe₃ thin films open the door for further advancements in optoelectronic device engineering. Their ability to operate effectively in the UV-Vis range makes them particularly valuable for next-generation photodetectors that require broad-spectrum sensitivity and rapid response characteristics (1).

Future Research Directions

While these findings mark a significant step forward, further optimization is needed to enhance the device’s overall efficiency. The researchers suggest that refining fabrication techniques and exploring different device architectures could lead to improved responsivity and detectivity. Additionally, integrating HgPSe₃ with other 2D materials may enable new functionalities and expanded wavelength detection capabilities (1,2).

As the study demonstrates, HgPSe₃ thin flakes hold great promise as light-absorbing materials for photodetection applications. Their structural stability, efficient spectral response, and rapid signal processing capabilities position them as a strong contender in the ever-evolving field of 2D optoelectronics. With further research, HgPSe₃-based photodetectors could play a vital role in developing more advanced and efficient optical sensing technologies (1,2).

References

(1) Chuang, Y.-L.; Yao, Y.-T.; Yang, B.-C.; Lue, C.-S.; Kuo, C.-N.; Lee, M.-L.; Sheu, J.-K. Raman Spectroscopy of HgPSe₃ Thin Flakes and Its Application to Near UV-to-Visible Photodetectors. Chin. J. Phys. 2025, 93, 409–417. DOI: 10.1016/j.cjph.2024.12.016

(2) de Simoni, B.; Rybak, M.; Antonatos, N.; Herman, A. P.; Ciesiołkiewicz, K.; Tołłoczko, A. K.; Peter, M.; Piejko, A.; Mosina, K.; Sofer, Z.; Kudrawiec, R. Electronic Band Structure and Optical Properties of HgPS₃ Crystal and Layers. J. Phys. Chem. C 2024, 128 (22), 9270–9280. DOI: 10.1021/acs.jpcc.4c00562