【Member Papers】High-performance DUV-visible dual-band photodetector enabled by β-Ga₂O₃/Au/Cs₂AgBiBr₆ heterojunction with sandwich architecture

      Researchers from the Northeast Normal University have published a dissertation titled "High-performance DUV-visible dual-band photodetector enabled by β-Ga₂O₃/Au/Cs₂AgBiBr₆ heterojunction with sandwich architecture" in Materials Today Physics.

Project Support

      This work was supported by the National Key R&D Program of China (2021YFA0716404), the funding from Jilin Province (No. 20220502002GH), the National Natural Science Foundation of China (No. 52302166, No. 62404038, No. 12474164), the Science Technology Program of Jilin Province (20240602060RC), the National Postdoctoral Program for Innovative Talents (BX20230064), the Fundamental Research Funds for the Central Universities (No. 2412023QD004, No. 2412024QD009), the funding from Education Department of Jilin Province (JJKH20241412KJ), the Research Projects of the Education Office of Jilin Province (JJKH20250300KJ), Jilin Province Development and Reform Commission (2022C040-1), the Postdoctoral Fellowship Program of CPSF (GZC20240240).

Background

      Dual-band photodetectors (PDs) covering the range from DUV to visible light regions are pivotal for optical communications, environmental monitoring, and sensing imaging. While silicon, transition metal dichalcogenides, and black phosphorus have been extensively explored for dual-band photodetection, these materials typically operate in the visible and near-infrared regions, with a weak response in the DUV region. To enable efficient DUV detection within dual-band PDs, ultra-wide bandgap semiconductors, such as Mg_xZn_1-xO, Al_xGa_1-xN, diamond, BN, and β-Ga₂O₃ have been utilized as the DUV absorbing layers. Among these, β-Ga₂O₃ has gained prominence due to its direct bandgap (E_g ≈ 4.9 eV) and superior thermal/chemical stability. 

Abstract

      High sensitivity and fast response dual-band photodetectors (PDs) covering the deep-ultraviolet (DUV) to visible spectrum are highly desired for industrial and scientific applications. Herein, a sandwich-architecture PD covering the range from DUV to visible was prepared by stacking a β-Ga₂O₃ DUV absorbing layer, interdigitated Au electrodes, and a Cs₂AgBiBr₆ (CABB) visible absorbing layer. At 5 V bias voltage, the sandwich-architecture PD achieves responsivities of 37.74 mA/W at 240 nm and 0.07 mA/W at 450 nm with microsecond response time, respectively, which is superior to the PDs using monolayer β-Ga₂O₃ or CABB. Furthermore, it demonstrates self-powered dual-band detection capability with maximum responsivity of 8.13 mA/W. Enhanced performance arises from two synergistic mechanisms: a vertical built-in electric field at the β-Ga₂O₃/CABB interface spatially separates photogenerated carriers, while a higher hole mobility in CABB facilitates the charge collection under a lateral bias field between Au electrodes. Importantly, the β-Ga₂O₃/Au/CABB PD demonstrates high-resolution images under 240 nm and 450 nm illumination. This work provides a route for developing high-performance DUV-visible dual-band photodetectors, highlighting their potential for advanced multispectral imaging applications.

Highlights

      ● Sandwiched β-Ga₂O₃/Au/Cs₂AgBiBr₆ heterojunction enables efficient DUV-visible dual-band detection.

      ● Built-in field and high hole mobility of Cs₂AgBiBr₆ synergistically boost carrier separation and speed.

      ● The device achieves self-powered operation and high-resolution multispectral imaging capability under both DUV and visible illumination.

Conclusion

      In summary, we have successfully developed a DUV-visible dual-band photodetector through the integration of β-Ga₂O₃ with all-inorganic double perovskite CABB in a sandwich architecture. The β-Ga₂O₃/Au/CABB PD demonstrates dual-band performance from DUV to visible regions, achieving responsivities of 37.74 mA/W at 240 nm and 0.07 mA/W at 450 nm under 5 V bias. The device also exhibits fast response times of 0.34/2.65 ms and 0.014/1.45 ms at 240 nm and 450 nm, respectively. Furthermore, it achieves a maximum responsivity of 8.13 mA/W in self-powered operation. The synergistic effects of vertical built-in electric field and the high hole mobility in CABB enable charge separation while suppressing carrier recombination. High-resolution imaging of the β-Ga₂O₃/Au/CABB PD under 240 nm and 450 nm illumination was demonstrated. This work not only significantly extends the functional capabilities of DUV detectors but also paves the way for multifunctional applications across diverse spectral ranges.