Manipulable and Hybridized,Ultralow‐Threshold Lasing in a Plasmonic Laser Using Elliptical InGaN/GaN Nanorods

Manipulating stimulated‐emission light in nanophotonic devices on scales smaller than their emission wavelengths to meet the requirements for optoelectronic integrations is a challenging but important step. Surface plasmon polaritons (SPPs) are one of the most promising candidates for sub‐wavelength optical confinement. In this study, based on the principle of surface plasmon amplification by the stimulated emission of radiation (SPASER), III‐Nitride‐based plasmonic nanolaser with hybrid metal–oxide–semiconductor (MOS) structures is designed. Using geometrically elliptical nanostructures fabricated by nanoimprint lithography, elliptical nanolasers able to demonstrate single‐mode and multimode lasing with an optical pumping power density as low as 0.3 kW cm^?2 at room temperature and a quality Q factor of up to 123 at a wavelength of ≈490 nm are achieved. The ultralow lasing threshold is attributed to the SPP‐coupling‐induced strong electric‐field‐confinement in the elliptical MOS structures. In accordance with the theoretical and experimental results, the size and shape of the nanorod are the keys for manipulating hybridization of the plasmonic and photonic lasing modes in the SPASER. This finding provides innovative insight that will contribute to realizing a new generation of optoelectronic and information devices.     

Catalyst‐Free GaN Nanorods Synthesized by Selective Area Growth

GaN nanorod formation on Ga‐polar GaN by continuous mode metalorganic chemical vapor deposition selective area growth (MOCVD SAG) is achieved under a relatively Ga‐rich condition. The Ga‐rich condition, provided by applying a very low V/III ratio, alters the growth rates of various planes of the defined nanostructure by increasing relative growth rate of the semi‐polar tilted m‐plane {1–101} that usually is the slowest growing plane under continuous growth conditions. This increased growth rate relative to the non‐polar m‐plane {1–100} and even the c‐plane (0001), permits the formation of GaN nanorods with nonpolar sidewalls. In addition, a new growth mode, called the NH₃‐pulsed mode, is introduced, utilizing the advantages of both the continuous mode and the lower growth rate pulsed mode to form nanorods. Finally, nanorods grown under the different growth modes are compared and discussed.     

Ultraviolet photoresponse of ZnO nanostructured AlGaN/GaN HEMTs

We present the first active visible blind ultraviolet (UV) photodetector based on zinc oxide (ZnO) nanostructured AlGaN/GaN high electron mobility transistors (HEMTs). The ZnO nanorods (NRs) are selectively grown on the gate area by using hydrothermal method. It is shown that ZnO nanorod (NR)-gated UV detectors exhibit much superior performance in terms of response speed and recovery time to those of seed-layer-gated detectors. It is also found that the best response speed (~10 and~190 ms) and responsivity (~1.1×10⁵ A/W) were observed from detectors of the shortest gate length of 2 µm among our NR-gated devices of three different gate dimensions, and this responsivity is about one order higher than the best performance of ZnO NR-based UV detectors reported to date.     

衬底温度对ZnO纳米结构的影响

利用超声喷雾热解(USP)技术,以普通玻璃为衬底,制备了不同衬底温度下的系列ZnO薄膜.用扫描电镜(SEM)和X射线衍射(XRD)研究了衬底温度对ZnO结构的影响.结果表明,薄膜的微观结构随衬底温度变化显著.在410℃获得了ZnO纳米棒,纳米棒直径在50 nm左右,沿c轴择优生长,结晶质量较好.     

Penta‐Twinned Copper Nanorods: Facile Synthesis via Seed‐Mediated Growth and Their Tunable Plasmonic Properties

The use of seed‐mediated growth as a versatile approach to the synthesis of penta‐twinned Cu nanorods with uniform diameters and controllable aspect ratios is reported. The success of this approach relies on our recent synthesis of uniform Pd decahedra, with sizes in the range of 6–20 nm. The Pd decahedral seeds can direct the heterogeneous nucleation and growth of Cu along the fivefold axis to produce nanorods with uniform diameters defined by the lateral dimension of the original seeds. Due to a large mismatch in the lattice constants between Cu and Pd (7.1%), the deposited Cu is forced to grow along one side of the Pd decahedral seed, generating a nanorod with an asymmetric distribution of Cu, with the Pd seed situated at one of the two ends. According to extinction spectra, the as‐obtained Cu nanorods can be stored in water under the ambient conditions for at least six months without noticeable degradation. This excellent stability allows us to systematically investigate the size‐dependent surface plasmon resonance properties of the penta‐twinned Cu nanorods. With the nanorod transverse modes positioned at 560 nm, the longitudinal modes can be readily tuned from the visible to the near‐infrared region by controlling the aspect ratio.     

Fabrication of ZnO/SrTiO3 nanoarrays and its photoelectrochemical performances

The ZnO/SrTiO₃ nanomaterials were fabricated by a chemical conversion hydrothermal method in order to utilize the high electron transfer rate of one-dimensional ZnO nanorods and photocatalytic activity of SrTiO₃. The technological parameters, such as TiO₂ sol concentration, TiO₂ sol dipping cycle, Sr(NO₃)₂ concentration and reaction temperature, were investigated in the synthetic process and the reaction mechanism of the ZnO/SrTiO₃ nanomaterials was proposed. A photocurrent density of 7.53 mA/cm² was obtained for the as-prepared ZnO/SrTiO₃ photocatalyst, attributed to its improved absorption spectrum and appropriate nanostructure, which indicates a potential application in photoelectrochemical water splitting.     

Effect of Al doped ZnO on optical and photovoltaic properties of the p-Cu2O/n-AZO solar cells

Metal oxide thin films have fared so well in the semiconductor industry because of their superior physical, electrical, and optical properties. The applications of these materials in solar cells, biosensors, biomedicine, supercapacitors, photocatalysis, luminous materials, and laser systems are becoming increasingly popular. In this study, the influence of Al concentration on Cu₂O/AZO heterojunction thin films was examined systematically. First, arrays of n-ZnO and AZO rods were produced on an ITO substrate using a hydrothermal technique at 140 °C. Then, using an alkaline cupric lactate solution, a thin films of p-Cu₂O were electrodeposited at 60 °C onto the ZnO arrays. The structure and morphology of the produced materials and the solar cells were studied using X-ray diffraction and scanning electron microscopy. The optical measurements demonstrate a shift in the absorption edge with increasing Al content. Solar cells have been created with a device structure of ITO/ZnO/Cu₂O/Al and ITO/Al-doped ZnO/Cu₂O/Al configurations. The power conversion efficiency (?) of the inorganic solar cell with 6% Al-doped ZnO is ? = 0.282%, which is greater than the ? of the ZnO-based solar cell (? = 0.17%).     

Novel electrochemical sensing platform based on palygorskite nanorods/Super P Li carbon nanoparticles-graphitized carbon nanotubes nanocomposite for sensitive detection of niclosamide

We reported an one-pot ultrasonic-assisted method for the preparation of palygorskite nanorods/Super P Li carbon nanoparticles-graphitized carbon nanotubes (PNRs/SPCNPs-g-CNTs) nanocomposite, which was used to modify the glassy carbon electrode (GCE) for the fabrication of PNRs/SPCNPs-g-CNTs/GCE sensor. For the PNRs/SPCNPs-g-CNTs nanocomposite, PNRs with good stability presented large specific surface area and high adsorption, which promoted the enrichment of NA molecules on the electrode surface. SPCNPs with pearl chain-like nanostructure exhibited good electrical conductivity, and the combination of SPCNPs and g-CNTs with high graphitization degree formed an interconnected carbon conductive network with excellent electrical conductivity, which enhanced the charge transport efficiency. Moreover, the interconnected carbon conductive network of SPCNPs-g-CNTs not only promoted the dispersion degree of PNRs but also made up for the poor conductivity property of PNRs. When used for the detection of niclosamide (NA), an acceptable limit of detection (3.6 nM) was achieved at the PNRs/SPCNPs-g-CNTs/GCE sensor in linear NA concentration range of 0.01–10 μM. The PNRs/SPCNPs-g-CNTs/GCE sensor exhibited good reproducibility, repeatability, and anti-interference performance. For the practicability measurement, the fabricated sensor showed good practicability with satisfactory recoveries (97.0–102.7%) and low RSD values of 0.99–4.78% for the detection of NA in tap water and lake water samples.     

Oxygen vacancy-rich ZnO nanorods-based MEMS sensors for swift trace ethanol recognition

Ethanol vapor plays a significant role in the aspects of human health and industrial production, thus necessitating a swift, sensitive, and low-power ethanol detection in the field of future gas sensors. In this work, we prepared micro–electro–mechanical system ethanol sensors based on ZnO nanorods (NRs) and nanoparticles (NPs) for trace ethanol detection. Both ZnO samples were synthesized by a facile hydrothermal method. The comparison results exhibited that ZnO NRs based sensors prevailed over NPs-based counterparts in terms of sensitivity, optimal operation temperature, and reaction speeds. Briefly, that ZnO NRs-based sensors presented a large response (11.5 toward 5 ppm), fast response/recovery times (5 s/5 s), ultralow detection limit (400 ppb), and tiny power consumption (30 mW) at 245°C, surpassing most of recently reported ethanol sensors and commercial products based metal oxides. The abundant oxygen vacancies, large specific surface area, and porous structure were primarily responsible for the excellent sensor performance. This work also offers a facile and competitive approach to realize a sensitive and swift trace ethanol recognition with minimal power consumption, catering for the demanding requirements of future gas sensors in the fields of wearable devices and Internet of Things.