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In order to suppress the electron leakage to p-type region of near-ultraviolet GaN/In x Ga1–x N/GaN multiple-quantumwell (MQW) laser diode (LD), the Al composition of inserted p-type Al x Ga1–x N electron blocking layer (EBL) is optimized in an effective way, but which could only partially enhance the performance of LD. Here, due to the relatively shallow GaN/In0.04Ga0.96N/GaN quantum well, the hole leakage to n-type region is considered in the ultraviolet LD. To reduce the hole leakage, a 10-nm n-type Al x Ga1–x N hole blocking layer (HBL) is inserted between n-type waveguide and the first quantum barrier, and the effect of Al composition of Al x Ga1–x N HBL on LD performance is studied. Numerical simulations by the LASTIP reveal that when an appropriate Al composition of Al x Ga1–x N HBL is chosen, both electron leakage and hole leakage can be reduced dramatically, leading to a lower threshold current and higher output power of LD.

In this paper, we present a modeling study on the discharge characteristics driven by short pulsed voltages, focusing on the effects of pulse rise rate based on the fluid description of atmospheric plasmas. The numerical results show that the breakdown voltage of short pulsed discharge is almost linearly dependent on the pulse rise rate, which is also confirmed by the derived equations from the fluid model. In other words, if the pulse rise rate is fixed as a constant, the simulation results clearly suggest that the breakdown voltage is almost unchanged, although the amplitude of pulsed voltage increases significantly. The spatial distribution of the electric field and electron density are given to reveal the underpinning physics. Additionally, the computational data and the analytical expression also indicate that an increased repetition frequency can effectively decrease the breakdown voltage and current density, which is consistent with the experimental observation.

Two InGaN/GaN multiple-quantum-well (MQW) samples with identical epitaxial structures are grown at different growth rates via metal-organic chemical vapor deposition system. The room temperature photoluminescence intensity of the fast-grown sample is much stronger than that of the slow-grown one. In addition, the fast-grown sample has two luminescence peaks at low temperatures, and the height of main peak anomalously increases with increasing temperature below 100 K. Such improved emission efficiency and the untypical temperature-induced increase of peak height can be attributed to the carrier's transferring between two kinds of localized traps with different potential depth in the fast-grown sample, where the distribution of indium is seriously inhomogeneous. The enhanced fluctuation of indium is caused by the reduced migration time of adsorbed atoms due to the increased growth rate during the epitaxial growth of MQW region.

In this paper ZnO films are grown on GaAs/Al 2 O 3 substrates at different temperature by metal-organic chemical vapor deposition (MOCVD). The GaAs/Al 2 O 3 substrates are formed by depositing GaAs layer (∼35 nm) on the Al 2 O 3 substrate. The results of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) demonstrate that most of the Ga and As atoms form Ga–As bond and the GaAs layer does not present any orientation. The characters of the ZnO films grown on GaAs/Al 2 O 3 substrates are investigated by XRD, photoluminescence (PL), atomic force microscopy (AFM) and Raman scattering. Compared with ZnO film grown on Al 2 O 3 substrate, ZnO film prepared by our fabrication scheme has good crystal and optical quality. Meanwhile its grain size becomes bigger according to the AFM image. Raman analysis indicates that the intrinsic defects and the in-plane tensile stress are obviously reduced in ZnO/GaAs/Al 2 O 3 samples.

Heterojunction light-emitting diodes with ZnO/Si structure were fabricated on both high-resistivity (p) and low-resistivity (p+) Si substrates by metal–organic chemical vapor deposition technology. Fairly good rectifications were observed from the current–voltage curves of both heterojunctions. Ultraviolet (UV) and blue-white electroluminescence (EL) from ZnO layer were observed only from ZnO/p+-Si heterojunction under forward bias at room temperature (RT), while strong infrared (IR) EL emissions from Si substrates were detected from both ZnO/p-Si and ZnO/p+-Si heterojunctions. The UV and IR EL mechanisms have been explained by energy band structures. The realization of RT EL in UV–visible and IR region on Si substrate has great applicable potential for Si-based optoelectronic integrated circuits.

As a type of mechanical stimulation, extracorporeal shockwave (ESW) has been widely used in the clinic to treat bone fracture delayed union and non-unions. A large number of studies have shown beneficial effects of ESW in promoting fracture healing by inducing bone regeneration; however, the underlying mechanisms remain unclear. ESW has been shown to induce the production of prostaglandin E2 (PGE2), which is essential for gap junction intercellular communication in response to mechanical stress. Among the 19 known gap junction subunits, connexin43 (Cx43) is the most prevalent for mediating the response of mechanical stress. However, to our knowledge, the effect of ESW on Cx43 expression has not been reported before. Herein, we propose that a crosstalk between PGE2 and Cx43 is involved in the enhancement of osteogenesis induced by ESW. We review the currently available data to propose an unrevealed, but important mechanism via which ESW treatment affects osteogenic differentiation of bone marrow stromal cells.

ZnO thin films were deposited on semi-insulating (0 0 1) GaAs substrates at different growth conditions by metal-organic chemical vapour deposition. The effect of growth temperature and ambient oxygen partial pressure on the properties of the ZnO films was studied. It was found that these two important parameters affected the structure, crystallinity, surface morphology, and optical and electrical characteristics of the ZnO films. At the present growth conditions, the full width at half maximum of a ZnO (0 0 2) diffraction peak decreased to 0.185° at 610 °C under an oxygen partial pressure of 45 Pa. By increasing the oxygen partial pressure from 45 to 68 Pa, the surface of the ZnO films became smoother and the grain size smaller and more homogeneous. In addition, the near-band-edge emission and the deep-level emission in the photoluminescence spectra and the electrical properties of the ZnO thin films strongly depended on the ambient oxygen content.

Undoped n-ZnO thin films were successfully grown on p-Si (1 0 0) substrates by low-pressure metalorganic chemical vapour deposition (MOCVD). The c-axis oriented ZnO films were grown on Si at different temperatures using diethylzinc (DEZn) and oxygen (O2). The structural and optical properties of ZnO films were investigated using x-ray diffraction (XRD) and photoluminescence (PL) spectra, respectively. It is found that the ZnO film grown at 610 °C shows the best crystallinity and optical quality. Current–voltage (I–V) characteristics of all n-ZnO/p-Si heterojunctions exhibit nonlinear and rectifying characteristics with a small current leakage in the reverse direction. Junction leakage of the heterojunction deposited at 620 °C is higher than those of the other heterojunctions.

ZnO films were grown on GaAs(0 0 1)substrates at different surface treatment conditions at different growth temperatures by metal-organic chemical vapor deposition. ZnO(1 0 0) and ZnO(0 0 2) films that had different preferred orientations were grown according to different chemical etching condition. The crystallinity and optical properties of ZnO films were investigated with X-ray diffraction and the room-temperature photoluminescence spectra. Compared with ZnO(0 0 2) films, ZnO(1 0 0) films that have undergone variation at the preferred orientation have better crystal structure. Moreover, all samples have similar optical characteristics at the same growth temperature. For GaAs substrates etched under different conditions, the analysis results of X-ray photoelectroscopy show that the preferred orientation variations of ZnO films take place because rich As layer are formed in process of chemical etching.

Zinc oxide (ZnO) thin film was grown on CaF2 (11–21) substrate by metalorganic vapor phase epitaxy (MOVPE) and the structure, surface morphology and the opto-electrical properties of the film were investigated. It was found that preferential c-axis oriented ZnO film was highly transparent and quite smooth. In photoluminescence (PL) spectrum at 10 K, the neutral donor bound exciton (D0X) emission was identified at 3.362 eV (I4), the neutral acceptor bound exciton (A0X) emission at 3.346 eV (I9). Free A- and B-exciton emissions at 3.374 eV and 3.386 eV, respectively, as well as the phonon replicas of free A-exciton and D0X were also observed, indicating high optical quality of the ZnO film. Temperature-dependent PL spectra demonstrated that the free exciton emission was dominant at a temperature larger than 215 K. Hall measurement showed that the ZnO/CaF2 film exhibited n-type conduction, with the resistivity of 114 Ω cm and the Hall mobility of 15.7 cm2/Vs.

ZnO films were grown on (0 0 0 1) orientation (C-plane) and (0 1 ¯ 1 2) orientation (R-plane) sapphire substrates by low-pressure metalorganic chemical vapor deposition (MOCVD). The crystallinity, surface morphology and optical properties of ZnO films on C and R sapphires were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectrum and transmission spectrum, respectively. The XRD patterns of the films indicated that ZnO grew on C sapphire with a (0 0 0 2) orientation, while (1 1 2 ¯ 0) ZnO grew on R sapphire. The epitaxial relationships of the two films were determined by X-ray θ −2 θ and ϕ scans. The SEM images exhibited that the ZnO film grown on C sapphire had a columnar morphology, and that the ZnO film on R sapphire possessed a smooth and dense surface. The room temperature PL spectra showed that both of the films had a good optical quality, but the intensity of the near band-edge emission (NBE) peak of the ZnO film on C sapphire was more intense than that of the film on R sapphire. Besides, the transmission spectra showed that the two ZnO films were highly transparent in the visible region.

High-quality Mg x Zn 1− x O thin films were successfully grown on c -plane sapphire substrates by metal-organic chemical vapor deposition. The c -axis oriented Mg x Zn 1− x O films were deposited on sapphire at the temperature of 600–630°C. The structural and optical properties of Mg x Zn 1− x O films were investigated using X-ray diffraction (XRD) and the transmittance spectrum. MgO phase separation was not observed with Mg content up to x =0.39. The optical band gaps of Mg x Zn 1− x O alloys (0⩽ x ⩽0.39) range from 3.3 to 3.95 eV.

ZnO thin films were deposited on (001) Si substrate by low-pressure metalorganic chemical vapour deposition. Thermal annealing was performed at 800 °C in air for an hour. The effects of annealing on the surface morphology, stoichiometric ratio, structural and optical properties of ZnO films were investigated using scanning electron microscopy, x-ray photoemission spectroscopy (XPS), x-ray diffraction, Raman spectra and photoluminescence spectra. The resistivity of ZnO film increased to 1.25 × 102 Ω cm after annealing. It was found that the quality of ZnO film could be improved through annealing.

This article has been retracted at the request of the chief editor and authors. Reason: It contains ideas, concepts and paraphrased text from other sources (e.g., Appl. Phys. Lett 79 (2001) 943–945; J. Electrochem. Soc 148 (2001) G110–G113) without clear acknowledgement of the previous references. The judgement of the Editorial Board is that the author and co-authors have plagiarized a principal conclusion of the aforementioned Appl. Phys. Lett paper.

ZnO films were successfully deposited on c-plane sapphire substrates by low-pressure MOCVD using Diethylzinc (DEZn) and oxygen. The c-axis oriented ZnO films were grown on sapphire at the temperature of 600°C with different ZnO buffer layer thicknesses between 5 and 55 nm. The effects of ZnO buffer layer on crystallinity, surface morphology and optical properties of ZnO films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectrum, respectively. It was found that surface morphology, structural and optical properties of the films depended on the thickness of the buffer layer. The ZnO film grown on the 15 nm thick ZnO buffer layer shows a flat and dense surface, the good structural and optical properties.

High-quality ZnO films were grown on epi-GaN predeposited on c-Al 2 O 3 substrates using low-pressure metal-organic chemical vapor deposition (MOCVD). Detailed study of the X-ray diffraction spots and patterns by different diffractometers showed high structural perfection of the zinc oxide layer, which indicated that the growth of ZnO film was strongly c-oriented. The full-width at half-maximum (FWHM) of the ω -rocking curve was 0.39°. Surface morphology of the films studied by AFM showed that the growth of the ZnO film followed the regular hexagonal column structure with about 500 nm grain diameter. Zn and O elements in the deposited ZnO/GaN/Al 2 O 3 films were investigated and compared by X-ray photoelectron spectroscopy (XPS), in which the dissociative O and Zn atom peak was hardly observed. The ratio of O/Zn atoms of the film was about 1 with O-rich. Photoluminescence spectra of the ZnO films grown on epi-GaN showed dominating exciton emission peak, and the deep-level emission which was obvious on ZnO/Al 2 O 3 film had hardly been observed.

NH3-doped ZnO films were grown on 〈 0 2 2 4〉 oriented sapphire substrates at 610°C by metalorganic chemical vapor deposition. The crystal quality of the films was investigated by X-ray diffraction method, and the results indicated that the crystal quality of the doped film with NH3 flux 80 sccm (standard cubic centimeter per minute) is the best. At the same time, AFM images showed that this sample surface was also the most smooth. The Hall measurement results indicated that the film with 50 sccm NH3 flux showed p-type conductivity with hole concentrations of 1016 cm−3, and the other films with more NH3 flux still showed n-type, though their resistivity was very high. At last, the nature of nitrogen in the films was investigated by X-ray photoelectron spectroscopy (XPS). The results indicated that nitrogen in NH3 combines with zinc by N−3 at 50 sccm flux of NH3, and the O:Zn:N ratio is 40:45.5:14.6. As the flux increases, some hydrogen binding to nitrogen has been introduced into the ZnO films, which causes the resistivity to decrease again.

In this paper, high-quality ZnO film was grown by metal-organic chemical vapor deposition. Post-thermal annealing was performed on ZnO film in vacuum and oxygen condition. We could find only the X-ray diffraction pattern of (0 0 2) ZnO film indicating strong c-oriented growth. The quality of ZnO film was improved by thermal annealing in vacuum as confirmed by XRD and photoluminescence measurement. Raman scattering on as-grown ZnO film indicated that the quality of ZnO film was improved by thermal annealing in oxygen. The intensity of deep-level emission increased much after annealing in oxygen, while it nearly did not change after annealing in vacuum. We believed that the deep-level emission was related to zinc vacancy. The resistivity increased from 2.4 to 1100 Ω cm after thermal annealing in oxygen.

The ZnO films were deposited on (0 0 1)Si substrate by metal-organic chemical vapor deposition (MOCVD). Annealing was performed in air for 60 min at 800°C. The X-ray diffraction patterns of the samples showed sharp diffraction peaks for ZnO(0 0 2), which indicated that the films were highly c -axis oriented. Zn and O elements in the as-deposited ZnO film were investigated and compared with those in the annealed ZnO film by using X-ray Photoelectron Spectroscopy (XPS). XPS spectra showed that ZnO films changed from Zn-rich to O-rich after being annealed.

Undoped ZnO films were deposited on (0 0 1) silicon substrate by radio frequency (RF) magnetron sputtering. It was found that these properties strongly depended on frequency and O 2 /Ar gas flux ratio (expressed by k ) during the sputtering. The X-ray diffraction patterns of the samples showed sharp diffraction peaks for ZnO (0 0 2), which indicate that the as-sputtered flims were highly c -axis oriented. The band edge emission was observed in photoluminescence spectra at room temperature. The samples grown under certain conditions could generate stronger luminescence of ZnO. Besides, this paper analysed the relation between sputtering technics and crystal quality. The comparison among ZnO films deposited under different sputtering conditions indicated that crystalline quality was improved through changing the RF power and gas flux ratio of O 2 to Ar.

We deposited ZnO thin films on (0 0 1) Si substrate by metal-organic chemical vapor deposition. We found strong diffraction (0 0 2) peak at 34.76° and (0 0 4) peak at 72.84° indicating that ZnO thin film was strongly C-oriented. The full-width at half-maximum of (0 0 2) peak was 0.19°. ZnO film was highly transparent with a transmission ratio larger than 80% in the visible range. Ultraviolet emission was observed while deep level emission could hardly been observed in room temperature photoluminescence spectra. From temperature-dependent spectra of 300–80 K, we could observe neutral donor (D°X) bound exciton emission clearly and free-exciton emission dominated the spectrum when the temperature was above 220 K. X-ray photoemission spectra showed that ZnO film was Zn-rich with O:Zn=0.93:1.

The recent experimental observation shows that in the medium frequency range (300 kHz–3 MHz), there are two discharge modes, namely the Ω mode and hybrid mode. In this paper, a fluid model is explored to study the characteristics of these two discharge modes and their transitions. The numerical data indicate in the Ω mode the conduction current density is very low and the plasmas are mainly generated in the central region of gas gap, while the Ohmic heating takes place at the same region. For the hybrid mode, the ion density is very high in the sheath region, and the electrons are accelerated and produced in the sheath region, which are very similar to the characters of glow discharges in the low frequency region; meanwhile, a bulk plasma region with very high density is also formed in the center of gas gap, which is characterized by the α mode in the high frequency range. The mode transition among the glow discharge mode, hybrid mode and α mode is also investigated by varying the excitation frequency but with a fixed applied voltage. This simulation will deepen the understanding of mode transition in atmospheric discharges controlled by dielectric barriers for the whole excitation frequency range.

Atmospheric pressure non-equilibrium plasmas have attracted significant attention and have been widely used to inactivate pathogens, yet the mechanisms underlying the interactions between plasma-generated species and bio-organisms have not been elucidated clearly. In this paper, reactive molecular dynamics simulations are employed to investigate the mechanisms of interactions between reactive oxygen plasma species (O, OH, and O2) and β-1,6-glucan (a model for the C. albicans cell wall) from a microscopic point of view. Our simulations show that O and OH species can break structurally important C-C and C-O bonds, while O2 molecules exhibit only weak, non-bonded interactions with β-1,6-glucan. Hydrogen abstraction from hydroxyl or CH groups occurs first in all bond cleavage mechanisms. This is followed by a cascade of bond cleavage and double bond formation events. These lead to the destruction of the fungal cell wall. O and OH have similar effects related to their bond cleavage mechanisms. Our simulation r...

Temperature-dependent photoluminescence characteristics of organic-inorganic halide perovskite CH NH PbI Cl films prepared using a two-step method on ZnO/FTO substrates were investigated. Surface morphology and absorption characteristics of the films were also studied. Scanning electron microscopy revealed large crystals and substrate coverage. The orthorhombic-to-tetragonal phase transition temperature was ~140 K. The films' exciton binding energy was 77.6 ± 10.9 meV and the energy of optical phonons was 38.8 ± 2.5 meV. These results suggest that perovskite CH NH PbI Cl films have excellent optoelectronic characteristics which further suggests their potential usage in perovskitebased optoelectronic devices.

Recently, an urgent requirement of ultraviolet (UV) semiconductor laser with lower cost and higher performance has motivated our intensive research in zinc oxide (ZnO) material owing to its wide direct band gap and large exciton binding energy. Here, we demonstrate for the first time continuous-wave laser in electrically-pumped hollow polygonal microcavities based on epitaxial ZnO/MgO-core/shell nanowall networks structures and whispering gallery type resonant modes are responsible for the lasing action. The laser diodes exhibit an ultralow threshold current density (0.27 A/cm2), two or three orders of magnitude smaller than other reported UV-light semiconductor laser diodes to our knowledge. More importantly, the continuous-current-driven diode can achieve lasing up to ~430 K, showing a good temperature tolerance. This study indicates that nano-size injection lasers can be made from epitaxial semiconductor microcavities, which is a considerable advance towards the realization of practical UV coherent light sources, facilitating the existing applications and suggesting new potentials.

In this paper, we focus on a new small cell discovery signal which improves the detection probability in ultra-dense small cell scenario. Due to the severe inter-cell interference, the detection performance of primary synchronization signal (PSS) and secondary synchronization signal (SSS) is deteriorated in future ultra-dense small cell scenario in the 3rd Generation Partnership Project (3GPP) long term evolution (LTE) system. Thus the current supported 504 cell IDs may not be sufficient. To mitigate the impact of such inter-cell interference problems and improve the cell search performance with increasing number of detect target cells, we propose a novel defined auxiliary secondary synchronization signal (A-SSS) in cell search procedure. Our simulation results show that the detection probability of cell search can be improved effectively with the proposed method.

In order to further suppress the F–P lasing and increase the superluminescent power, the tilted ridge waveguide was introduced to the integrated superluminescent device [monolithic integration of the superluminescent diode (SLD) with semiconductor optical amplifier (SOA)[. By this means, high power 1.5 μm integrated superluminescent light source has been fabricated without anti-reflection (AR) coating. The F–P oscillations between the two cleaved facets were suppressed successfully compared with the device without ridge waveguide. More than 200 mW peak pulsed power was obtained under quasi-CW condition (0.1 ms pulse width, 10% duty cycle) by co-operation of the two integrated sections. The spectral FWHM is 25 nm.

The effect of the growth temperature on InN films grown at 500-725 °C by the pressurized–reactor metal organic vapor phase epitaxy (PR-MOVPE), which is designed to apply high nitrogen pressure to the reactor, has been studied. The growth temperature is found to greatly influence the surface morphology. The columnar islands appear at the growth temperature lower than and equal to 575 °C while the coalescence of islands occurs and forms continuous films at the growth temperature higher than 575 °C. Step-flow-like morphology is actually observed in the growth temperature range as high as 600-650 °C.However, at this high growth temperature range, the diffraction peak of metallic indium appears in XRD spectra. Therefore, it is in a dilemma to enhance the surface migration and prevent the precipitation of metallic indium. Our experimental results indicate that the growth temperature of InN can be increased using the pressurized growth conditions and the epitaxial temperature around 575 °C is best to obtain a good crystalline quality InN films without the precipitation of metallic indium at present growth pressure. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

This paper proposes an adaptive second sliding mode (SOSM) control strategy to control the stabilized platform of rotary steering drilling tool. Stabilized platform is typical uncertain system, and using traditional sliding mode control (SMC) needs to know the upper bound of uncertainty firstly, which cannot be satisfied for stabilized platform under work condition. Meanwhile, the input chattering phenomenon exists inevitably. Therefore, using adaptive SOSM method can solve the two problems. SOSM controller eliminates the input chattering, and the design of adaptive tuning law for SOSM controller overcomes the limitation of prior knowledge about the uncertain upper bound. Simulation results show that the proposed control strategy can make stabilized platform achieve good control performance and robustness.

The differential resistance curves of GaAs- and GaN-based laser diodes (LDs) are experimentally and numerically investigated. It is found that the dependence of the differential resistance upon the injection current differs in the GaAs- and GaN-based LDs mainly in two aspects. The first is the kink polarity of the differential resistance in the vicinity of the threshold current, and the second is the behavior of the differential resistance curve beyond the threshold current. Self-consistent calculation results suggest that the LD kink and its polarity are determined by the superposition effects of the n-side, active and p-side regions of LDs. It is found that this kink mainly differs in the differential resistance curves of the active region, while the difference in the behavior of the differential resistance curve after the lasing threshold is ascribed to a resistance change in the p-side region caused by a reduced ideality factor.

Vertically aligned O-polar ZnO nanowall networks were prepared on N-polar p-graded Al x Ga1− x N/sapphire substrates by metal–organic chemical vapor deposition. Further, heterojunction light-emitting diodes based on O-polar n-ZnO/N-polar p-graded Al x Ga1− x N were fabricated. A strong and narrow ultraviolet emission at 388 nm, originating from ZnO, was observed under forward bias. The hole injection efficiency of the proposed diode was significantly enhanced owing to the existence of polarization-induced two-dimensional hole gas at the n-ZnO/p-graded Al x Ga1− x N heterointerface, thereby yielding an enhanced light output power. This work provides an alternative path towards the realization of high-performance ZnO-based ultraviolet diodes.

We have investigated the electron affinity of Si-doped AlN films (N Si = 1.0 × 1018–1.0 × 1019 cm−3) with thicknesses of 50, 200, and 400 nm, synthesized by metalorganic chemical vapor deposition (MOCVD) under low pressure on the n-type (001)6H–SiC substrates. The positive and small electron affinity of AlN films was observed through the ultraviolet photoelectron spectroscopy (UPS) analysis, where an increase in electron affinity appears with the thickness of AlN films increasing, i.e., 0.36 eV for the 50-nm-thick one, 0.58 eV for the 200-nm-thick one, and 0.97 eV for the 400-nm-thick one. Accompanying the x-ray photoelectron spectroscopy (XPS) analysis on the surface contaminations, it suggests that the difference of electron affinity between our three samples may result from the discrepancy of surface impurity contaminations.

The influence of Shockley–Read–Hall (SRH) non-radiative recombination on efficiency droop is investigated for two similar InGaN/GaN multiple-quantum-well green light-emitting diodes (LEDs) with quite different luminescence efficiency. The high-efficiency diode exhibits a pronounced efficiency peak followed by a significant droop as injection current increases, while the low-efficiency sample shows a relatively small droop. Combining with the recombination rate equations, our analysis reveals that, in comparison with the high-efficiency sample, in the low-efficiency diode the injected carrier density in InGaN well layers is decreased at high currents due to the strong SRH process, leading to an apparently reduced droop. This may be a possible physical mechanism responsible for the linkage between the low efficiency and the small efficiency droop.

O-polar ZnO films were grown on N-polar p-GaN/sapphire substrates by photo-assisted metal-organic chemical vapor deposition, and further heterojunction light-emitting diodes based O-polar n-ZnO/N-polar p-GaN were proposed and fabricated. It is experimentally demonstrated that the interface polarization of O-polar n-ZnO/N-polar p-GaN heterojunction can shift the location of the depletion region from the interface deep into the ZnO side. When a forward bias is applied to the proposed diode, a strong and high-purity ultraviolet emission located at 385 nm can be observed. Compared with conventional Zn-polar n-ZnO/Ga-polar p-GaN heterostructure diode, the ultraviolet emission intensity of the proposed heterojunction diode is greatly enhanced due to the presence of polarization-induced inversion layer at the ZnO side of the heterojunction interface. This work provides an innovative path for the design and development of ZnO-based ultraviolet diode.

ZnO samples with a double-layer structure and top nanorod arrays on the bottom film layer were grown by metal-organic chemical vapor deposition at a temperature range from 340 to 400 °C. The ZnO nanorods show excellent optical quality and no obvious defect related emission can be detected below 40 K except for I6 line and the surface bound exciton emission. The free exciton emission and its phonon replicas dominate the near band edge emission between 40 and 295 K. For the film layer, the temperature-dependent Hall measurements showed that the conduction region is degenerate. In the conduction region, the carrier mobility is mainly limited by the grain boundary effect, which can be weakened by thermal annealing. The conduction mechanism in this region before and after annealing can be fitted by a uniform and a non-uniform conduction model, respectively. The results indicate that grain boundary effects strongly limit the mobility and consume large amounts of carriers by the trap states. Furthermore, we propose a qualitative model to explain the expansion of the conduction regions by annealing. It reveals a mechanism for the improvement of electrical properties of polycrystalline thin films by annealing treatments.

Vertically conducting deep-ultraviolet (DUV) light-emitting diodes (LEDs) with a polarization-induced backward-tunneling junction (PIBTJ) were grown by metal–organic chemical vapor deposition (MOCVD) on 6H-SiC substrates. A self-consistent solution of Poisson–Schrödinger equations combined with polarization-induced theory was applied to simulate the PIBTJ structure, energy band diagrams, and free-carrier concentration distribution. AlN and graded Al x Ga1− x N interlayers were introduced between the PIBTJ and multiple quantum well layers to avoid cracking of the n-Al0.5Ga0.5N top layer. At a driving current of 20 mA, an intense DUV emission at ∼288 nm and a weak shoulder at ∼386 nm were observed from the AlGaN top layer side. This demonstrates that the PIBTJ can be used to fabricate vertically conducting DUV LED on SiC substrates.

An optimal design method of operating parameters in hydrogen cyanide (HCN) production process is presented. Firstly the soft sensor model of HCN conversion rate is established by BP neural network. Then considering the practical constraints of operating parameters and taking the maximum HCN conversion rate as objective function, an improved particle swarm optimization (IPSO) algorithm is introduced to optimize the operating parameters, which takes into account the dynamic inertia weight and the particle average position to avoid falling into local optimum and accelerate the convergence. Simulation results with actual production data show that, compared with genetic algorithm (GA) optimization, this method can obtain the optimal operating parameters of the HCN production process.

Coordinated multi-point transmission/reception (CoMP) has been identified as an important way of mitigating interference and improving spectral efficiency for cell edge users in LTE-A system. However, current CoMP studies mainly focus on joint transmission (JT), dynamic point selection (DPS) and coordinated scheduling/beamforming (CS/CB) which all fall into closed-loop category. When considering medium or high mobility users, closed-loop CoMP seems less effective, while open-loop CoMP is more preferred, which is similar to that observed between closed-loop and open-loop single user multiple-input multiple-output (SU-MIMO). In this paper, we propose open-loop CoMP transmission frameworks for both spatial multiplexing and transmit diversity. We design our open-loop CoMP schemes by reusing long term evolution (LTE) open-loop SU-MIMO structures as much as possible to alleviate standardization efforts, and especially consider support for demodulation reference signals (DM-RS) which will be prevalent in future LTE-Advanced systems. Simulation results verify the effectiveness of our proposed open-loop CoMP schemes.

To promote the research on the growth of high-quality InN films attractive to the application for both optical and electronic devices, the pressurized-reactor metalorganic-vapor-phase epitaxy (PR-MOVPE) system which can overcome the high equilibrium-vapor-pressure of nitrogen between solid and vapor phases is originally developed. In addition to this system, the N-polar growth technique developed in the growth of GaN is introduced. As a result, the dense InN films with atomic steps are successfully grown. From the struggle of the research on high quality InN, the subject of the phase purity is also arisen. The pole figure measurements make the growth condition for a pure InN with a wurtzite structure. The phase purity is almost determined by the growth temperature. These results will pave the way to high-quality InN.

Considering the influence of uncertainty as unknown nonlinearity, parameters perturbation and random waves disturbance to the fin stabilizer system during ship sailing in heavy sea, the random wave model is built and a robust controller based on adaptive backstepping, sliding mode and RBF neural network is proposed. Adaptive backstepping and sliding mode control is the main controller and RBF neural network is used to compute the upper bound value of uncertainty which is composed of unknown nonlinearity, parameters perturbation and random waves disturbance, then the system stability is analyzed by using the Lyapunov theory. The simulation results show that the control strategy is effective to decrease roll motion of fin stabilizer system in different sea conditions and has strong robust stability to overcome the uncertainty.

According to the status quo of advanced industrial process control, this paper proposes to structure advanced cntrol platform based on iFIX software1. Both in the platform can do simulation research, and can also be used for the practical control process. The collection and analysis of related field data play an important role in this advanced control platform. The collection of relevant data for this cabin automated monitoring system, the key technologies of transmission and processing, as well as describes the method of report production and data import into the database system are expounded in this paper.

A new adaptive irregular modulation technique is proposed for Turbo iterative detected multi-antenna system with different bit mapping schemes or (and) modulation schemes used in different transmit antennas. The modulation scheme and the bit mapping scheme can be adaptively chosen according to the time varying channel quality to improve the channel throughput. When combining the proposed approach and the irregular modulation scheme, it can provide more flexible adaptation to the current channel quality. Simulation results show that using this adaptive technique, the system can converge earlier without changing the system throughput; meanwhile, system using this adaptive method can have higher system throughput compared with conventional adaptive method.