In the past decades, the doping of ZnO one‐dimensional nanostructures has attracted a great deal of attention due to the variety of possible morphologies, large surface‐to‐volume ratios, simple and ...low cost processing, and excellent physical properties for fabricating high‐performance electronic, magnetic, and optoelectronic devices. This article mainly concentrates on recent advances regarding the doping of ZnO one‐dimensional nanostructures, including a brief overview of the vapor phase transport method and hydrothermal method, as well as the fabrication process for photodetectors. The dopant elements include B, Al, Ga, In, N, P, As, Sb, Ag, Cu, Ti, Na, K, Li, La, C, F, Cl, H, Mg, Mn, S, and Sn. The various dopants which act as acceptors or donors to realize either p‐type or n‐type are discussed. Doping to alter optical properties is also considered. Lastly, the perspectives and future research outlook of doped ZnO nanostructures are summarized.
Recent developments in doping ZnO 1D nanostructured photodetectors are reviewed with a focus on the type of photodetector and the methods of synthesis and fabrication. In this review, the typical fabrication methods and structure–property relationships of these photodetectors are discussed. The photodetector performances of differently doped materials are also summarized and compared.
In this letter, a WO 3 nanoparticle gas sensor was fabricated using an ICP-assisted hot wire system. The results of experiments indicated that the sensitivity became smaller when the measured ...temperature increased. It was also found that the WO 3 nanoparticle gas sensor prepared at an annealing temperature of 400°C had the greatest sensitivity. The measured sensitivity for a micro-electromechanical system type WO 3 nanoparticle gas sensor was found to be around 3.22, 3.91, 5.02, 7.52, 11.68, and 15.93 when the operating temperature of the micro-heater was 150°C and the concentration of injected NO gas was 100, 150, 200, 250, 300, and 350 ppb, respectively.
A tri-band bandpass filter designed based on a stub-loaded step-impedance resonator (SIR) is proposed. The resonant behavior of the stub-loaded SIR is analyzed. By properly controlling the impedance ...ratio K 1 , the length ratio (α) and the length ratio (r) of the stub-loaded SIR, the center frequencies are designed at 1.575, 2.4, and 3.5 GHz, respectively, corresponding to the GPS, WLAN and WiMAX applications. Furthermore, a 0° feed structure is used to provide at least one transmission zero near passband edge of each passband, resulting in high selectivity. Experimental results show good agreement with the simulated results.
Band gap opening and engineering is one of the high priority goals in the development of graphene electronics. Here, we report on the opening and scaling of band gap in BN doped graphene (BNG) films ...grown by low-pressure chemical vapor deposition method. High resolution transmission electron microscopy is employed to resolve the graphene and h-BN domain formation in great detail. X-ray photoelectron, micro-Raman, and UV–vis spectroscopy studies revealed a distinct structural and phase evolution in BNG films at low BN concentration. Synchrotron radiation based XAS-XES measurements concluded a gap opening in BNG films, which is also confirmed by field effect transistor measurements. For the first time, a significant band gap as high as 600 meV is observed for low BN concentrations and is attributed to the opening of the π–π* band gap of graphene due to isoelectronic BN doping. As-grown films exhibit structural evolution from homogeneously dispersed small BN clusters to large sized BN domains with embedded diminutive graphene domains. The evolution is described in terms of competitive growth among h-BN and graphene domains with increasing BN concentration. The present results pave way for the development of band gap engineered BN doped graphene-based devices.
This letter presents a design of a compact ultra-wideband (UWB) bandpass filter (BPF), which can exhibit an UWB response from 3.1 to 9.9 GHz with low insertion loss (IL) of 0.8 dB and an extremely ...broad stopband region from 10.9 to 25.1 GHz with high rejection level of 20 dB. This UWB BPF is simply constructed by using only one single-stage parallel-coupled line and two rectangular stub resonators. In this design, the rectangular stub resonators provide an exciting mode to enhance the desired UWB response and also create tunable transmission zeros to extend a wide stopband by controlling the impedance ratio (R) properly. The filter was fabricated and measured to verify the design concept.
We demonstrate in-plane gate transistors based on the molybdenum disulfide (MoS
)/graphene hetero-structure. The graphene works as channels while MoS
functions as passivation layers. The weak ...hysteresis of the device suggests that the MoS
layer can effectively passivate the graphene channel. The characteristics of devices with and without removal of MoS
between electrodes and graphene are also compared. The device with direct electrode/graphene contact shows a reduced contact resistance, increased drain current, and enhanced field-effect mobility. The higher field-effect mobility than that obtained through Hall measurement indicates that more carriers are present in the channel, rendering it more conductive.
This study explores the Cu wire corrosion-related issues and provides solutions for evaluation & analysis as the Automotive Electronics Council (AEC) continually formulates industry specification and ...qualification procedures for evolving Cu wire-bonding technology. Evaluation of molding resin attributes concerning about the preferential Intermetallic Compounds (IMCs) corrosion and formation of oxidation layer in the Cu–Al interface during accelerated reliability stress test (bias HAST) is discussed. Failure mechanism for Cu–Al system is microgalvanic corrosion accompanied with crevice/pitting corrosion-induced deterioration in the presence of moisture and ion impurity from resin encapsulatants. Failure analysis techniques conduct on corrosion-induced broken stitch bond issue are proposed and root cause is identified. Electrochemical studies of Au, Cu, Pd-doped Cu (PCC) and Ag alloy wire presents here for further understanding the corrosion behavior in wire-bonding packages. Potentiodynamic polarization is used to investigate the electrolyte property and corrosion performance of these specimen in the corrosive medium. The results provide vital information on the Cu corrosion study not only in ball bonds but also in stitch bonds which are of practical value to the current industry under “design for reliability” (DfR) approach to product development.
•Selective Cu–Al IMC corrosion during bHAST were investigated.•Additives of EMC would highly influence the lifetime of device.•Failure mechanism for Cu–Al system were presented.•Electrochemical studies of Au, Cu, Pd-doped Cu (PCC) and Ag alloy wire were also addressed.
Carbon nanotubes (CNTs) have been demonstrated to be one of the most interesting materials for gas sensing. This paper applies a simple method for the direct transfer of high-density CNTs from a ...SiO2/Si substrate to a flexible substrate for carbon dioxide (CO2), ammonia (NH3), and isopropyl alcohol gas sensing at room temperature. The flexible gas sensor exhibited high sensitivities of 4.8%, 5.4%, and 5.2% at room temperature for ambient CO2, NH3, and isopropyl alcohol gas concentrations of 800 ppm, respectively. In addition, the gas response of the CNT-based chemiresistor is attributed to p-type conductivity in the Au-modified semiconducting CNTs. Very good repeatability of the sensor response to gas concentration is demonstrated, representing a major step toward the low-cost large-scale production of this class of device.
We report the growth of ZnO nanowires on ZnO:Ga/glass templates and the fabrication of laterally grown ZnO nanowire ethanol sensors. It was found that growth direction of the nanowires depends ...strongly on growth parameters. It was also found that resistivity of the fabricated sensor decreased upon ethanol gas injection. By introducing 1500
ppm ethanol gas, it was found that the device response were around 20%, 35%, 58% and 61% when the gas sensor was operated at 180
°C, 230
°C, 260
°C and 300
°C, respectively. It was also found that the device response at 300
°C were around 18%, 26%, 43%, 55% and 61% when the concentration of injected ethanol gas was 50
ppm, 100
ppm, 500
ppm, 1000
ppm and 1500
ppm, respectively.
An ultraviolet-enhanced (UV-enhanced) nitric oxide (NO) sensor based on silver-doped zinc oxide (ZnO) nanoflowers is developed using a low-cost hydrothermal method. The results indicate that silver ...(Ag) ions were doped into the ZnO nanostructure successfully, thus changing the morphology. In the high-resolution transmission electron microscopy images, we also found that some Ag ions were separated out onto the surface of the ZnO nanoflowers and that the Ag-doped and Ag nanoparticles improved the sensing property. The NO sensing property increased from 73.91 to 89.04% through the use of a UV light-emitting diode (UV-LED). The response time was approximately 120 s without the UV-LED, and the UV-enhanced Ag-doped ZnO nanoflower sensor exhibited a reduced response time (60 s). The best working temperature could be reduced from 200 to 150 °C using UV light illumination, and it was found that the NO response increased by 15.13% at 150 °C. The UV photoresponse of the Ag-doped ZnO nanoflowers and the mechanisms by which the improvement of NO sensing property occurred through the use of UV light illumination are discussed. The property of the gas sensor can be calibrated using a self-photoelectric effect under UV light illumination. These interesting UV-enhanced Ag-doped ZnO nanoflowers are viable candidates for practical applications.
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