Photovoltaic Effect and Evidence of Carrier Multiplication in Graphene Vertical Homojunctions with Asymmetrical Metal Contacts

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• 作者：Jing-Jing Chen ; Qinsheng Wang ; Jie Meng ; Xiaoxing Ke ; Gustaaf Van Tendeloo ; Ya-Qing Bie ; Junku Liu ; Kaihui Liu ; Zhi-Min Liao ; Dong Sun ; Dapeng Yu
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：September 22, 2015
• 年：2015
• 卷：9
• 期：9
• 页码：8851-8858
• 全文大小：578K
• ISSN：1936-086X

文摘

Graphene exhibits exciting potentials for high-speed wideband photodetection and high quantum efficiency solar energy harvest because of its broad spectral absorption, fast photoelectric response, and potential carrier multiplication. Although photocurrent can be generated near a metal鈥揼raphene interface in lateral devices, the photoactive area is usually limited to a tiny one-dimensional line-like interface region. Here, we report photoelectric devices based on vertical graphene two-dimensional homojunction, which is fabricated via vertically stacking four graphene monolayers with asymmetric metal contacts. The devices show excellent photovoltaic output with excitation wavelength ranging from visible light to mid-infrared. The wavelength dependence of the internal quantum efficiency gives direct evidence of the carrier multiplication effect in graphene. The simple fabrication process, easy scale-up, large photoresponsive active area, and broadband response of the vertical graphene device are very promising for practical applications in optoelectronics and photovoltaics.