Physical Review B

With large surface-to-volume ratios and Debye length comparable to their small sizes, one-dimensional inorganic nanostructures have extensively been investigated and widely used to fabricate high-performance nanoscale electronic and optoelectronic devices This feature article reviews the state-of-the-art research activities that focus on the one-dimensional inorganic nanostructures and their photodetector applications It begins with a survey of one-dimensional inorganic nanostructures and the fundamentals of photodetectors Some remarkable photoresponse characteristics are then presented, which are organized into sections covering several kinds of important nanostructures, such as ZnO, V 2 O 5 , ZnS, In 2 Se 3 , InSe, CdS, CdSe, ZnSe, Sb 2 Se 3 , ZrS 2 , Ag 2 S, and Zn x Cd 1-x Se Each section describes the corresponding photodetective properties in detail Finally, the article concludes with some perspectives and outlook on the future developments in the field

Recent Developments in One-Dimensional Inorganic Nanostructures for Photodetectors

This review gives a comprehensive report on the microwave-assisted synthesis of metal oxides for applications in the field of gas sensing. In recent years, microwave heating technology has gained importance in the synthesis of metal oxides because of its faster, cleaner and cost effectiveness than conventional thermal heating. Further, due to the peculiarity of microwave heating mechanism, the synthesis of metal oxides in different nanostructured forms by microwave-assisted methods has been widely pursued and the nanomaterials thus obtained have been applied as sensing elements in chemoresistive gas sensors. Their gas sensing performances are here described and discussed in detail, emphasizing the improved characteristics compared with materials produced by conventional synthesis procedures.

Microwave-assisted synthesis of metal oxide nanostructures for gas sensing application: A review

Novel self-powered nanoscale photodetectors that can work without an external power source, which have great application potential in next-generation nanodevices that operate wirelessly and independently, are being widely studied. This review aims to give a comprehensive summary of the state-of-the-art research results on self-powered nanoscale photodetectors. An introduction of recent progress on Schottky junction photodetectors is provided. Two types of Schottky junctions are discussed in detail: metal-semiconductor and semiconductor-graphene junctions. Next, recent developments of p-n junction photodetectors are highlighted, including homojunction and heterojunction photodetectors. Then, piezo-phototronic effect enhanced photodetection performances of Schottky junctions and p-n junctions are discussed. Then, significant results on the photoelectrochemical-cell-based photodetector and integrated self-powered nanosystem are presented, followed by a systematic comparison of different types of photodetectors. Finally, a summary of the previous results is given, and the major challenges that need to be addressed in the future are outlined. The hope is that this review can provide valuable insights into the current status of self-powered photodetectors and spur new structure and device designs to further enhance photodetection performance.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/smll.201701848

Self-Powered Nanoscale Photodetectors.

Development of cardiac troponin-I biosensor based on boron nitride quantum dots including molecularly imprinted polymer.

High quality, vertically aligned ZnO nanorods were grown on a silicon substrate, using microwave-assisted chemical bath deposition with poly (vinyl alcohol)-Zn(OH)2 nanocomposites as seed layer. The structure and surface morphology of the prepared ZnO nanorod arrays were characterized using X-ray diffraction and scanning electron microscopy. The optical properties were assessed using photoluminescence measurements; the results showed a high-intensity UV peak, and a lower intensity, broader visible peak. Upon exposure to 395 nm light at a zero-bias voltage, the UV detector showed a high sensitivity of 8000% and fast response and recovery times of 25 and 22 ms, respectively.

High sensitivity and fast response and recovery times in a ZnO nanorod array/p-Si self-powered ultraviolet detector

Optical properties of CdS micro/nanocrystalline structures prepared via a thermal evaporation method

ZnO nanorod arrays were grown on a flexible Kapton tape using microwave-assisted chemical bath deposition. High crystalline properties of the produced nanorods were proven by X-ray diffraction patterns and field emission scanning electron microscopy. Additionally, the photoluminescence spectrum showed higher UV peaks compared with visible peaks, which indicates that the ZnO nanorods had high quality and low number of defects. The metal-semiconductor-metal (MSM) configuration was used to fabricate UV and hydrogen gas detectors based on the ZnO nanorods grown on a flexible Kapton tape. Upon exposure to 395 nm UV light, the UV device exhibited fast response and decay times of 37 ms and 44 ms, respectively, at a bias voltage of 30 V. The relative sensitivities of the gas sensor made of the ZnO nanorod arrays, at hydrogen concentration of 2 %, at room temperature, 150 °C and 200 °C, are 0.42, 1.4 and 1.75 respectively.

Fast UV detection and hydrogen sensing by ZnO nanorod arrays grown on a flexible Kapton tape

Cadmium sulfide (CdS) nanowires (NWs) were prepared by the solvothermal method using ethylenediamine as a solvent. Two sets of CdS NWs were synthesized at 160 and 200 °C for various reaction durations (3⋅5, 7, and 24 h). Scanning/tunneling electron microscopy was used to examine the surface morphology of the grown NWs. Their dimensions are found to depend on the reaction temperature and duration. The CdS NWs grown at 200 °C for all durations are longer than those prepared at 160 °C, with diameters ranging from 15 to 40 nm. A three-armed structure is exhibited by all the samples. The grown CdS NWs display a hexagonal wurtzite phase and grows along the $\mathbf {\left \langle {001}\right \rangle }$
 direction. The optical absorption of the grown NWs shows a sharp absorption edge with a blueshift, which indicates an expansion of the optical band gap. All prepared samples show two emission peaks in their photoluminescence spectra. The emission peak location depends on the reaction temperature and duration. The CdS NWs prepared at 160 °C show a sharp band–band emission compared with those prepared at 200 °C. Raman analysis indicates that the optical properties of the grown NWs are enhanced with increased temperature and reaction duration.

/pdf/solvothermal-growth-of-single-crystal-cds-nanowires-2hr5q7b4ad.pdf

Solvothermal growth of single-crystal CdS nanowires

Cadmium sulfide (CdS) nanoflowers, nanoplates and nanofire structures were synthesized by chemical bath deposition (CBD) on porous silicon (PS). The PS substrates were prepared by electrochemical etching method using alternating current (ACPS) and direct current (DCPS). Scanning electron microscopy (SEM) revealed that the CdS fabricated on ACPS had two nanostructures, nanoflowers and nanoplates while the CdS on DCPS showed a novel structure named nanofire. X-ray diffraction patterns showed that the CdS nanocrystalline structured in watzite (hexagonal) phase. Photoluminescence (PL) of CdS nanoflowers and nanoplates structures showed a high intensity with blue-shift compared with nanofire structure. Furthermore, Raman spectra of CdS nanostructures showed red shift of peaks positions.

/pdf/cds-nanocrystalline-structured-grown-on-porous-silicon-1xchj5jmfs.pdf

S. J. Kasim

Papers

High sensitivity and fast response and recovery times in a ZnO nanorod array/p-Si self-powered ultraviolet detector

Optical properties of CdS micro/nanocrystalline structures prepared via a thermal evaporation method

Fast UV detection and hydrogen sensing by ZnO nanorod arrays grown on a flexible Kapton tape

Solvothermal growth of single-crystal CdS nanowires

CdS NANOCRYSTALLINE STRUCTURED GROWN ON POROUS SILICON SUBSTRATES VIA CHEMICAL BATH DEPOSITION METHOD