Near-Ultraviolet-Sensitive Graphene/Porous Silicon Photodetectors

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• 作者：Jungkil Kim ; Soong Sin Joo ; Kyeong Won Lee ; Ju Hwan Kim ; Dong Hee Shin ; Sung Kim ; Suk-Ho Choi
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：December 10, 2014
• 年：2014
• 卷：6
• 期：23
• 页码：20880-20886
• 全文大小：551K
• ISSN：1944-8252

文摘

Porous silicon (PSi) is recognized as an attractive building block for photonic devices because of its novel properties including high ratio of surface to volume and high light absorption. We first report near-ultraviolet (UV)-sensitive graphene/PSi photodetectors (PDs) fabricated by utilizing graphene and PSi as a carrier collector and a photoexcitation layer, respectively. Thanks to high light absorption and enlarged energy-band gap of PSi, the responsivity (R_i) and quantum efficiency (QE) of the PDs are markedly enhanced in the near-UV range. The performances of PDs are systemically studied for various porosities of PSi, controlled by varying the electroless-deposition time (t_d) of Ag nanoparticles for the use of Si etching. Largest gain is obtained at t_d = 3 s, consistent with the maximal enhancement of R_i and QE in the near UV range, which originates from the well-defined interface at the graphene/PSi junction, as proved by atomic- and electrostatic-force microscopies. Optimized response speed is 鈭?0 times faster compared to graphene/single-crystalline Si PDs. These and other unique PD characteristics prove to be governed by typical Schottky diode-like transport of charge carriers at the graphene/PSi junctions, based on bias-dependent variations of the band profiles, resulting in novel dark- and photocurrent behaviors.

Keywords:

graphene; porous Si; Schottky diode; photodetectors; near-ultraviolet