Hierarchical-Oriented Si/ZnO Heterostructured Nanowires

Chong, Su Kong; Lim, Eng Liang; Yap, Chi Chin; Chiu, Wee Siong; Dee, Chang Fu; Rahman, Saadah Abdul

doi:10.1166/sam.2014.1768

Cited by 5 publications

(5 citation statements)

References 34 publications

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“…High-resolution transmission electron microscopy (HRTEM) micrographs of the samples were taken via a JEOL HRTEM (JEM-2100F), operating at an accelerating voltage of 200 kV. Characterization by X-ray diffraction and photoluminescence have been previously performed and published [ 17 , 18 ] (see Additional file 1 ). A preliminary PEC cell testing has been carried out to characterize the photocurrent.…”

Section: Methodsmentioning

confidence: 99%

Hierarchical Si/ZnO trunk-branch nanostructure for photocurrent enhancement

Dee¹,

Chong²,

Rahman³

et al. 2014

Nanoscale Res Lett

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Hierarchical Si/ZnO trunk-branch nanostructures (NSs) have been synthesized by hot wire assisted chemical vapor deposition method for trunk Si nanowires (NWs) on indium tin oxide (ITO) substrate and followed by the vapor transport condensation (VTC) method for zinc oxide (ZnO) nanorods (NRs) which was laterally grown from each Si nanowires (NWs). A spin coating method has been used for zinc oxide (ZnO) seeding. This method is better compared with other group where they used sputtering method for the same process. The sputtering method only results in the growth of ZnO NRs on top of the Si trunk. Our method shows improvement by having the growth evenly distributed on the lateral sides and caps of the Si trunks, resulting in pine-leave-like NSs. Field emission scanning electron microscope image shows the hierarchical nanostructures resembling the shape of the leaves of pine trees. Single crystalline structure for the ZnO branch grown laterally from the crystalline Si trunk has been identified by using a lattice-resolved transmission electron microscope. A preliminary photoelectrochemical (PEC) cell testing has been setup to characterize the photocurrent of sole array of ZnO NR growth by both hydrothermal-grown (HTG) method and VTC method on ITO substrates. VTC-grown ZnO NRs showed greater photocurrent effect due to its better structural properties. The measured photocurrent was also compared with the array of hierarchical Si/ZnO trunk-branch NSs. The cell with the array of Si/ZnO trunk-branch NSs revealed four-fold magnitude enhancement in photocurrent density compared with the sole array of ZnO NRs obtain from VTC processes.

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Section: Methodsmentioning

confidence: 99%

Hierarchical Si/ZnO trunk-branch nanostructure for photocurrent enhancement

Dee¹,

Chong²,

Rahman³

et al. 2014

Nanoscale Res Lett

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“…A variety of 3D branched Si NW HSs have been developed to utilize their distinct properties for emerging applications in photovoltaics, photocatalysis, photoelectrochemical water splitting, supercapacitors, Li-ion batteries etc. Several 3D branched Si NW-based HS systems have been studied, including oxide semiconductors, such as Si/ZnO [51,[59][60][61]130], Si/TiO 2 [50,[53][54][55], Si/SiO 2 [58], group IV semiconductors, such as Si/Ge [56], III-V semiconductors, such as Si/InP [56], Si/GaN [57], Si/GaAs [56], Si/GaP [56], Si/InGaN [52], II-VI semiconductors, such as Si/CdS [56], metals such as Si/Au [131], metallic silicide and alloys, such as Si/Au [56], Si/Co [132] etc. Figure 4 shows a glimpse of different types of branched Si NW HS reported in the literature.…”

Section: Branched Nanowire Heterostructuresmentioning

confidence: 99%

Silicon nanowire heterostructures for advanced energy and environmental applications: a review

Ghosh

Giri

2016

Nanotechnology

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Semiconductor nanowires (NWs), in particular Si NWs, have attracted much attention in the last decade for their unique electronic properties and potential applications in several emerging areas. With the introduction of heterostructures (HSs) on NWs, new functionalities are obtained and the device performance is improved significantly in many cases. Due to the easy fabrication techniques, excellent optoelectronic properties and compatibility of forming HSs with different inorganic/organic materials, Si NW HSs have been utilized in various configurations and device architectures. Herein, we review the recent developments in Si NW HS-based devices including the fabrication techniques, properties (e.g., light emitting, antireflective, photocatalytic, electrical, photovoltaic, sensing etc) and related emerging applications in energy generation, conversion, storage, and environmental cleaning and monitoring. In particular, recent advances in Si NW HS-based solar photovoltaics, light-emitting devices, thermoelectrics, Li-ion batteries, supercapacitors, hydrogen generation, artificial photosynthesis, photocatalytic degradation of organic dyes in water treatment, chemical and gas sensors, biomolecular sensors for microbial monitoring etc have been addressed in detail. The problems and challenges in utilizing Si NW HSs in device applications and the key parameters to improve the device performance are pointed out. The recent trends in the commercial applications of Si NW HS-based devices and future outlook of the field are presented at the end.

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“…Optical energy gap (E g ) of the samples was calculated using Tauc's relation, as: ሺߙ‫ܧ‬ሻ ൌ ‫ܧ‪ሺ‬ܤ‬ െ ‫ܧ‬ ሻ , where m is 0.5 for allowed indirect allowed transition [44]. The absorption coefficient, α can be calculated from the optical transmission (T) and reflectance (R) as: ߙ ൌ ଵ ௗ ݈݊ ቀ ଵିோ ் ቁ. Tauc's plots of the WO 3 thin films and Si/WO 3 core-shell NWs are shown in Figure S2 and S3, respectively; while the E g were obtained by using the method shown in the literature [45].…”

Section: Resultsmentioning

confidence: 99%

“…Optical energy gap (E g ) of the samples was calculated using Tauc's relation, as: (aE) m ¼ B(E À E g ), where m is 0.5 for allowed indirect allowed transition. 44 The absorption coefficient, a can be calculated from the optical transmission (T) and reectance (R) as: a ¼ 1 d ln 1 À R T . Tauc's plots of the WO 3 thin lms and Si/WO 3 core-shell NWs are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Single reactor deposition of silicon/tungsten oxide core–shell heterostructure nanowires with controllable structure and optical properties

2015

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We report a controllable growth of silicon/tungsten oxide (Si/WO 3 ) core-shell heterostructure nanowires via a two-step route using a home-built plasma-assisted hot-wire chemical vapour deposition reactor. Uniform coating of WO 3 shell indicates a clear preferential for growth on the single crystalline Si nanowires. Structure and crystallinity of the WO 3 shell are strongly dependent on the filament temperature (T f ). X-ray diffraction patterns and micro-Raman spectra suggested that there was a structure evolution from amorphous into crystallite WO 3 monoclinic structure when T f was increased to 1300 o C and above. The WO 3 shell exhibits stoichiometric tungsten trioxide structure as identified by micro-Raman and X-ray photoemission spectra analyses, which showed only W 6+ -O vibration modes for the former analysis and W 6+ energy band for the latter. Microstructure, crystal lattice, interface and growth orientation of the core-shell nanowires were recognized using a high resolution transmission electron microscopy. Our results showed that the core-shell nanowires had preserved the optical transmittance of Si core at a longer wavelength, while showing an additional transmission band edge at a shorter wavelength due to tungsten oxide coating. Their optical absorption increased to 80% and above in visible region, owing to the one-dimensional Si NWs backbone. Optical band gap of the core-shell nanowires showed a variation from 2.4 to 1.8 eV with T f . This superior visible light absorption core-shell nanowires architecture subsequently enhanced the photocurrent density of the crystalline WO 3 nanostructures.

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Hierarchical-Oriented Si/ZnO Heterostructured Nanowires

Cited by 5 publications

References 34 publications

Hierarchical Si/ZnO trunk-branch nanostructure for photocurrent enhancement

Hierarchical Si/ZnO trunk-branch nanostructure for photocurrent enhancement

Silicon nanowire heterostructures for advanced energy and environmental applications: a review

Single reactor deposition of silicon/tungsten oxide core–shell heterostructure nanowires with controllable structure and optical properties

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