A Facile Integration of Zero- (I鈥揑II鈥揤I Quantum Dots) and One- (Single SnO2 Nanowire) Dimensional Nanomaterials: Fabrication of a Nanocomposite Photodetector with Ultrahigh Gain and Wide Sp

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• 作者：Meng-Lin Lu ; Chih-Wei Lai ; Hsing-Ju Pan ; Chung-Tse Chen ; Pi-Tai Chou ; Yang-Fang Chen
• 刊名：Nano Letters
• 出版年：2013
• 出版时间：May 8, 2013
• 年：2013
• 卷：13
• 期：5
• 页码：1920-1927
• 全文大小：480K
• 年卷期：v.13,no.5(May 8, 2013)
• ISSN：1530-6992

文摘

Via the integration of nanocomposites comprising I鈥揑II鈥揤I semiconductor quantum dots (QDs) decorated onto a single SnO₂ nanowire (NW), we successfully fabricate an ultrahigh-sensitivity and wide spectral-response photodetector. Under the illumination of He鈥揅d laser (325 nm) with the photon energy larger than the band gap of SnO₂ nanowire, remarkably, an ultrahigh photocurrent gain up to 2.5 脳 10⁵ has been achieved, and an enhancement factor can reach up to 700% (cf. bare SnO₂ NW) as light illumination onto the wire with an excitation intensity of 15 W/m². Also, a high gain value up to 1.3 脳 10⁵ is attained with the excited photon energy (488 nm) smaller than the band gap of SnO₂ nanowire. Several key factors contribute to ultrahigh photocurrent gain and wide spectral response. First, the decorated quantum dot processes an inherent nature of a large absorption coefficient above its band gap. Furthermore, the single SnO₂ nanowire provides an excellent conduction path for the photogenerated carriers as well as bears a large surface-to-volume ratio so that the coupling strength with quantum dots can be greatly enhanced. Most importantly, the spatial separation of photogenerated electrons and holes can be easily achieved due to the charge transfer arising from a type II band alignment between QDs and SnO₂ NW. This work thus demonstrates a new approach in which by selectively decorating suitable QDs the photocurrent gain of SnO₂ NWs can be greatly enhanced and extended to a wide spectral range of photoresponse previously inaccessible, providing a very useful guideline to create cheap, nontoxic, and highly efficient photodetectors.

Keywords:

Tin oxide nanowires; wide spectral response and high gain; nanocomposite photodetector; I鈭扞II鈭扸I quantum dots