A Facile Integration of Zero- (I–III–VI Quantum Dots) and One- (Single SnO₂ Nanowire) Dimensional Nanomaterials: Fabrication of a Nanocomposite Photodetector with Ultrahigh Gain and Wide Spectral Response

Abstract

Via the integration of nanocomposites comprising I-III-VI 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-Cd laser (325 nm) with the photon energy larger than the band gap of SnO2 nanowire, remarkably, an ultrahigh photocurrent gain up to 2.5 × 10(5) 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/m(2). Also, a high gain value up to 1.3 × 10(5) 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.

Ultrasmall SnO2 Nanocrystals: Hot-bubbling Synthesis, Encapsulation in Carbon Layers and Applications in High Capacity Li-Ion Storage

“…Nanostructured SnO 2 materials such as 0D nanocrystals (NCs) or quantum dots (QDs)34, 1D nanowires5 and/or nanorods6, 2D nanosheets/nanofilms4, and 3D-mesoporous SnO 2 7 have attracted wide interest due to their potential for use in a wide variety of applications such as gas sensors4, photocatalysts8, transparent electrodes for energy conversion9, and energy storage devices25. The wide applicability of nanostructured SnO 2 materials arises from their quantum size effect, large surface area, and high surface activity10.…”

Enhanced photocurrent gain by CdTe quantum dot modified ZnO nanowire

“…And then the diluted CdTe QDs was deposited on the NW surface by drop casting method [16]. Finally, the sample was baked at 100 • C for 5 min to evaporate the residual solution in order to achieve high coupling strength between the CdTe QDs and ZnO NWs.…”

“…Compared with the aforementioned methods, quantum dot (QD) modified NWs is a promising method for the QD's unique optical properties, such as tunable emission and absorption band, good photostability, and high light absorption coefficient etc. [16]. However, most of the QDs/NWs composites were used in photovoltaic cells devices to enhance the light-converting efficiency, there were rare reports using QDs/NW composites to fabricate the photodetectors.…”

“…However, most of the QDs/NWs composites were used in photovoltaic cells devices to enhance the light-converting efficiency, there were rare reports using QDs/NW composites to fabricate the photodetectors. Recently, CdSe and I-III-VI (CuInS 2 , CuInSe 2 ) QDs have been proved to enhance the photocurrent gain of SnO 2 NW, and an enhancement factor of up to 700% was realized [16,17]. For ZnO NW based photodetector, only Aga et al [28] reported the cadmium telluride (CdTe) decorated ZnO nanowire for enhancing the photocurrent gain.…”

Hierarchical Semiconductor Oxide Photocatalyst: A Case of the SnO2 Microflower

“…As an important direct wide band gap semiconductor (Eg = 3.6 eV), SnO 2 possesses the excellent optical, gas sensing and photocatalytic properties [12][13][14][15][16][17]. Thus far, the reported SnO 2 nanostructures are mostly one dimensional (1D) structures, such as nanorods [18][19][20], nanotubes [21][22][23], and nanowires [24][25][26][27] and so on. Only a few successful examples of SnO 2 nanosheets have been reported [28][29][30], which may be attributed to the difficulty in controlling the oxidation process of Sn 2+ to Sn 4+ such that the mixed phases of SnO 2 and SnO will coexist in the product [31].…”