Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Aug;40(8):e70277.
doi: 10.1002/bio.70277.

Tunneling-Induced Amplification of Photoexcited Electrons in ITO-Graphene Heterojunction Photodetectors for High-Performance Photodetection

Jin Heung Kim  1   2 , Jae Sun You  1 , Doyun Kim  1 , Bontu Habtamu Geremew  1 , Velu Subash  1 , Velu Manikandan  1 , Kwang Soup Song  1
Affiliations

Tunneling-Induced Amplification of Photoexcited Electrons in ITO-Graphene Heterojunction Photodetectors for High-Performance Photodetection

Jin Heung Kim et al. Luminescence. 2025 Aug.

Abstract

In this study, we investigate the performance of an Indium tin oxide (ITO)-graphene heterojunction photoreactor, fabricated using the RF-sputtering method. The ITO thin film, with a thickness of 23.4 nm and a grain size of 12.5 nm, was deposited onto graphene under an oxygen-to-argon gas ratio of 1:20. The ITO area was precisely controlled using a metal mask, resulting in an ITO-graphene heterojunction structure. The photoreactor exhibited a significant increase in current under forward bias, with a cut-in voltage of 2.8 V and leakage current under reverse bias. Schottky junction characteristics were observed between the ITO and graphene. At -0.2 V bias, the dark current was 0.55 nA/cm2, while the device demonstrated high photoresponsivity (1.56 A/W) and photodetectivity (9 × 1012 Jones). Notably, the device showed tunneling-induced amplification of the photocurrent, approximately 44 times, due to photoelectrons tunneling from the graphene side to the ITO layer. This tunneling effect plays a crucial role in enhancing the device's performance. Additionally, the device demonstrated self-powered operation, with rise and fall times of 0.544 and 0.613 ms, respectively, under modulated light. These findings underscore the potential of ITO-graphene heterojunctions for high-performance photodetectors, with tunneling-induced amplification as a key mechanism for improved photoresponse.

Keywords: ITO; Schottky junction; heterojunction; photodetector; self‐amplifying graphene.

PubMed Disclaimer

References

    1. B. Y. Zhang, T. Liu, B. Meng, et al., “Broadband High Photoresponse From Pure Monolayer Graphene Photodetector,” Nature Communications 4 (2013): 1811.
    1. C. O. Kim, S. Kim, D. H. Shin, et al., “High Photoresponsivity in an All‐Graphene p–n Vertical Junction Photodetector,” Nature Communications 5 (2014): 3249.
    1. Y.‐P. Hsieh, C.‐H. Yen, P.‐S. Lin, et al., “Ultra‐High Sensitivity Graphene Photosensors,” Applied Physics Letters 104 (2014): 041110.
    1. X. Guo, W. Wang, H. Nan, et al., “High‐Performance Graphene Photodetector Using Interfacial Gating,” Optica 3 (2016): 1066–1070.
    1. L.‐H. Zeng, M.‐Z. Wang, H. Hu, et al., “Monolayer Graphene/Gemanium Schottky Junction as High‐Performance Self‐Driven Infrared Light Photodetector,” ACS Applied Materials and Interfaces 5 (2013): 9362–9366.