Optical and electrical properties of ZnO thin film containing nano-sized Ag particles

Low-temperature crystallized ZnO thin film was achieved by sol–gel process using zinc acetate dihydrate and 2-methoxyethanol as starting precursor and solvent, respectively. Ag nanoparticles were prepared with uniform size at 4.4 nm by spontaneous reduction method of Ag 2-ethylhexanoate in dimethyl sulfoxide (DMSO). The optical and electrical properties of ZnO thin films containing various contents of Ag-nanoparticles were monitored. Light scattering and charge emission and scattering behaviors of Ag nanoparticles in ZnO film were found. The incorporation of Ag nanoparticles into Al-doped ZnO film was also investigated. The optical transmittance was not degraded but the increase of electrical sheet resistance was found. The effect of Al-dopant on the transmittance and electrical sheet resistance of ZnO film was found too great to distinguish the positive effect of the incorporation of Ag nanoparticles into Al-doped ZnO thin films.     

Delay-Dependent Robust Stability of Stochastic Uncertain Systems with Time Delay and Markovian Jump Parameters

This paper is concerned with the delay-dependent stability for a class of stochastic uncertain systems with time delay and Markovian jump parameters. The uncertainties considered in this paper are norm-bounded and governed by the Markov process. Un like the topics in the existing literature, the stability criterion is expressed in terms of linear matrix inequalities, which can be efficiently solved by using a convex-optimization algorithm. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.     

Virtual fine delay line using one-stage inverter delay

A virtual fine delay line (VFDL) using only two ring oscillators and counters can cover a wide frequency operation range clock without adding any additional delay line stage. The proposed ring oscillator can easily make a unit delay as a one-stage inverter. The VFDL achieves fine resolution of less than 60 ps and small circuit area with two clock cycles lock-in time.     

互调干扰信号的特征识别

在复杂电磁信号环境中,实际存在为数不少的互调干扰信号,对这类信号的有效分析识别,是无线电监测工作需要重点关注解决的难题。对互调干扰信号在幅度特征和频谱峰值特征两个方面的特性进行了分析,给出了互调干扰信号识别的思路。     

High efficiency red phosphorescent organic light-emitting diodes using a spirobenzofluorene type phosphine oxide as a host material

High efficiency red phosphorescent organic light-emitting diodes have been developed using a spirobenzofluorene type phosphine oxide (SPPO2) as a host material. The SPPO2 had a high glass transition temperature of 119 °C and a smooth surface morphology with a surface roughness less than 1 nm. The red device with the SPPO2 as a host showed a quantum efficiency of 14.3% with a current efficiency of 20.4 cd/A.     

Cathodoluminescence and Field-Emission Properties of β-Ga2O3 Nanobelts

β-Ga₂O₃ nanobelts were synthesized using a vapor transport process in a controlled ambient. Structural characterization revealed that the as-synthesized samples consisted of monoclinic β-Ga₂O₃ nanobelts, and the presence of gallium-associated defects was verified using cathodoluminescence (CL). The formation of gallium-associated defects was explained by the insufficiency of the supply of cations, generating gallium vacancies on the (010) facet during growth. Furthermore, field-emission measurements indicated that β-Ga₂O₃ nanobelts exhibited defect-related electron emission. The turn-on fields of β-Ga₂O₃ nanobelts increased significantly with the degree of structural defects. For a sample prepared under 15% ambient oxygen, Fowler–Nordheim (F–N) analysis revealed two distinct field-enhancement factors of 1194 and 276, respectively. A correlation between field emission and structural defects was proposed. The experimental results demonstrate the presence of gallium-associated defects, which behave as electron traps, degrading the electron field-emission properties of β-Ga₂O₃ nanobelts.     

Efficient electron beam condensing for low-energy microcolumn lithography

Low-energy electron beam lithography has been performed with a microcolumn by adopting a new technique that condenses the electron beam efficiently. To increase the probe current while keeping the kinetic energy of electrons sufficiently low, the negative or positive bias has been applied to the accelerator electrode, which reduces the divergence of the electron beam and hence makes more electrons pass through the microcolumn. With this technique, the probe current more than 1 nA has been achieved, which is large enough for the practical application of microcolumn lithography even when the kinetic energy of electrons is as low as 160 eV. The results of microcolumn lithography by using the condensed electron beam with a low-energy of 160 and 327 eV are also presented.     

Partial adaptive nulling on a monopulse phased array antenna system

A partial phase-only nulling (PPON) algorithm has been developed and evaluated on a 496-element monopulse phased array antenna system which employs five-bit phase shifters. Using this PPON algorithm allows nulls in the far-field pattern to be steered to the desired directions for a phased array equipped with low-resolution phase shifters to perform simultaneous nulling in the sum and two difference patterns in the environment of multiple jammers. Simulated and experimental patterns are illustrated     

X-band HBT VCO with high-efficiency CB buffer amplifier

A monolithic AlGaAs-GaAs HBT VCO with common-base (CB) buffer amplifier was demonstrated at X-band. Overall efficiency of 30% was achieved with 93-mW output power at 9.8 GHz. The MMIC chip is only 1 mm×2 mm, including the monolithic varactor diode. The circuit design offers several unique advantages: (1) the CB buffer amplifier reduces the frequency-pull effect from the external load; (2) the design for the oscillation condition and the output impedance match for power are separated; and (3) the overall efficiency can be high. A step-by-step design procedure is discussed