High Detectivity Graphene‐Silicon Heterojunction Photodetector |
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Authors: | Xinming Li Miao Zhu Mingde Du Zheng Lv Li Zhang Yuanchang Li Yao Yang Tingting Yang Xiao Li Kunlin Wang Hongwei Zhu Ying Fang |
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Affiliation: | 1. National Center for Nanoscience and Technology, Zhongguancun, Beijing, P. R. China;2. State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, P. R. China;3. Department of Chemical Engineering, Tsinghua University, Beijing, P. R. China;4. CAS Center for Excellence in Brain Science and Intelligence Technology, 320 Yue Yang Road, Shanghai, P. R. China |
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Abstract: | A graphene/n‐type silicon (n‐Si) heterojunction has been demonstrated to exhibit strong rectifying behavior and high photoresponsivity, which can be utilized for the development of high‐performance photodetectors. However, graphene/n‐Si heterojunction photodetectors reported previously suffer from relatively low specific detectivity due to large dark current. Here, by introducing a thin interfacial oxide layer, the dark current of graphene/n‐Si heterojunction has been reduced by two orders of magnitude at zero bias. At room temperature, the graphene/n‐Si photodetector with interfacial oxide exhibits a specific detectivity up to 5.77 × 1013 cm Hz1/2 W‐1 at the peak wavelength of 890 nm in vacuum, which is highest reported detectivity at room temperature for planar graphene/Si heterojunction photodetectors. In addition, the improved graphene/n‐Si heterojunction photodetectors possess high responsivity of 0.73 A W?1 and high photo‐to‐dark current ratio of ≈107. The current noise spectral density of the graphene/n‐Si photodetector has been characterized under ambient and vacuum conditions, which shows that the dark current can be further suppressed in vacuum. These results demonstrate that graphene/Si heterojunction with interfacial oxide is promising for the development of high detectivity photodetectors. |
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Keywords: | graphene detectivity noise spectra heterojunctions photodetectors |
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