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To achieve ultra-high gain deep-ultraviolet (DUV) detectors based on ultra-wide bandgap semiconductors comparable with those of bulky photomultiplier tubes (PMTs), avalanche photodiodes have usually been adopted. However, the high-operation voltage (∼100 V) is not compatible with monolithic integration. Herein, it is demonstrated that the ultra-high gain DUV photodetectors (PDs) with low operation voltages (<5 V) can be achieved by using the synergistic effect of surface states and deep defects in a type-Ib single-crystal diamond (SCD) substrate. The overall photoresponse, such as the sensitivity, dark current, spectral selectivity, and response speed, of the diamond DUV-PDs can be simply tailored by the surface hydrogen or oxygen termination of the SCD substrate. The DUV responsivity and external quantum efficiency are more than 2.5 × 104A/W and 1.4 × 107%, respectively, at 220 nm-wavelength light, comparable with those of PMTs. The DUV/visible light rejection ratio (R220 nm/R400 nm) is as high as 6.7 × 105. The depletion of the 2D hole gas by deep nitrogen defect provides a low dark current and the filling of the ionized nitrogen upon DUV illumination induces a huge photocurrent. The synergistic effect of the surface states and the bulk deep defects opens the avenue for the development of DUV detectors compatible with integrated circuits.

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  This is the peer reviewed version of the following article: K. Gu, K. Wu, Z. Zhang, T. Ohsawa, J. Huang, Y. Koide, M. Toda, M. Liao, Synergistic Effect of Surface States and Deep Defects for Ultrahigh Gain Deep-Ultraviolet Photodetector with Low-Voltage Operation. Adv. Funct. Mater. 2025, 35, 2420238, which has been published in final form at https://doi.org/10.1002/adfm.202420238. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

Keyword: Diamond, photodetector

Date published: 2024-12-04

Publisher: Wiley

Journal:

• Advanced Functional Materials (ISSN: 1616301X) vol. 35 issue. 14

Funding:

• Japan Society for the Promotion of Science 22K18957
• Japan Society for the Promotion of Science 24H00287

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5443

First published URL: https://doi.org/10.1002/adfm.202420238

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Updated at: 2025-12-04 08:30:33 +0900

Published on MDR: 2025-12-04 08:22:26 +0900