Aluminum plasmonics enriched ultraviolet GaN photodetector with ultrahigh responsivity, detectivity, and broad bandwidth

Abhishek Dubey^1*, Ragini Mishra³, Chang-wei, Cheng², Lih-Juann, Chen¹, Shangjr Gwo^2,3,4, Ta-Jen Yen¹

¹Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan
²Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
³Institute of Nano Engineering and Microsystems, National Tsing Hua University, Hsinchu, Taiwan
⁴Research Center of Applied Science, Academia Sinica, Taipei, Taiwan

* Presenter:Abhishek Dubey, email:adubeyphy@gmail.com

Plasmonic enhanced photodetectors have been well explored in the visible to the IR spectrum. Several plasmonic materials have been given promised results in this regime. To explore the plasmonic properties in the Ultraviolet (UV) regime, the aluminum (Al) film shows enormous potential to operate in the deep UV to near UV spectrum. Therefore, an epitaxial single‐crystalline Al film, an abundant metal with high plasma frequency and low intrinsic loss is fabricated, on a wide bandgap semiconductive gallium nitride (GaN) to form a UV photodetector. Therefore, the Epitaxial-Al film is grown by PA-MBE (Plasma assisted Molecular beam epitaxy) method on GaN/Al₂O₃ substrate. CMOS compatible techniques are used to make subwavelength metasurface and Schottky diode. The ultrahigh responsivity (670 A/W) and detectivity (1.48 × 10¹⁵(cm √Hz)/ W) are observed at 355 nm wavelength. In addition, owing to coupling among nanoholes, the bandwidth expands substantially, encompassing the entire UV range. Finally, a Schottky contact is formed between the single‐crystalline Al and the GaN substrate, resulting in a fast temporal response. To the best knowledge, the presented detectivity is the highest compared with those of other reported GaN photodetectors.

Keywords: Ultraviolet Plasmonics, epitaxial Aluminum film, GaN, photodetector