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Arbutin is a well-known tyrosinase inhibitor that prevents the formation of melanin through the inhibition of tyrosinase. Therefore, it has been widely used as a cosmetic skin-lightening agent. Arbutin is able to scavenge free radicals within cells and previous studies have found that it also exhibited useful activities for the treatment of diuresis, bacterial infections, and cancer, as well as anti-inflammatory and anti-tussive activities. This study analyzed the effects of arbutin on streptozotocin (STZ)-induced diabetes mellitus in a murine model. Healthy male adult C57BL/6 mice (7 weeks old) were randomly allocated into one of the following three groups of six animals: Normal control with no STZ administration, STZ-induced diabetes, and STZ-induced diabetes treated with 0.3 g/kg/day of arbutin. After 12 days, the levels of insulin, C-peptide, and HbA1c were measured in serum, and the expression and enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were analyzed in pancreatic tissues by western blotting. Arbutin was found to significantly inhibit the increase in blood glucose and the loss of body weight in diabetic mice. Arbutin increased plasma insulin levels in mice with STZ-induced diabetes, whereas there was no detection of insulin in untreated diabetic mice. In addition, there was an increased expression and activity of SOD, CAT, and GPx in diabetic mice treated with arbutin. This investigation demonstrated that arbutin possesses antioxidant activities and can alleviate symptoms of type-1 diabetes mellitus (T1DM) in mice.

The two-dimensional (2D) materials have been widely developed recently in material characteristics with advanced optical and electrical properties, and they have been extensively studied as candidates for the next generation of optoelectronic devices. This review will mainly focus on the preparation methods and the light emitting applications of 2D transition metal dichalcogenides (TMDs), 2D black phosphorene (BP) and 2D perovskites. The review will first introduce the preparation methods for TMDs and BP. Due to the variations of band structure, exciton binding energies and light-matter interaction in TMDs and BP, the different light emitting devices (LEDs) designs based on TMDs and BP will be discussed and summarized. Then the review will turn the focus to 2D perovskites, starting with a description of the preparation methods for the different structural perovskites. In order to review and summarize the achievements of 2D perovskites-based LEDs, the high efficiency perovskites LEDs are discussed. Finally, the review will present challenges, opportunities, and outlook for the future development of 2D materials-based light emitting applications.

Most recently, III–V based ultrathin solar cells have attracted considerable attention for their inherent advantages, such as increased tolerance to defect recombination, efficient charge carrier separation, photon recycling, flexibility, and reduced material consumption. However, so far, almost all reported devices make use of conventional doped p-i-n kind of structures with a wide-bandgap III–V lattice-matched epitaxial window layer, for passivation and reduced contact recombination. Here, we show that a high-efficiency device can be obtained utilizing an InP thin film of thickness as low as 280 nm, without the requirement of a conventional p-n homojunction or epitaxial window layer. This is achieved by utilizing a wide-bandgap electron and hole selective contacts for electrons and holes transport, respectively. Under ideal conditions [assuming interface recombination velocity (IRV) = 103 cm/s and bulk lifetime = 1 μs], the proposed solar cell structure can achieve efficiency as high as 28%. Although, in the presence of bulk and interface Shockley–Read–Hall recombination, the efficiency reduces, still for bulk minority carrier lifetime as low as 2 ns and an IRV as high as 105 cm/s, an efficiency of ∼22% can be achieved with InP thickness as low as 280 nm. The proposed device structure will be beneficial in cases where the growth of controlled p-n homojunction and window layer can be tedious as in case of low-cost deposition techniques, such as thin-film vapour–liquid–solid and close-spaced vapour transport.

Graphene oxide-ZnS (GOZS) nanocomposites were successfully prepared by solvothermal method. The microstructure, morphology and nonlinear optical properties of the obtained GOZS nanocomposites were characterized by XRD, Raman, SEM, TEM, Mapping, UV–vis and open aperture Z-scan test. The results show that ZnS particles with a diameter of about 20 nm are evenly distributed on the GO surface. And GOZS exhibited enhanced nonlinear absorption and optical limiting (OL) action under ultrafast (1030 nm, 340 fs) excitation. The theoretical nonlinear coefficients of GO, ZnS, GOZS(4:5), GOZS(2:5) and GOZS(1:5) at 20.8 GW/cm2 are calculated as 27.6 cm/GW, 25.4 cm/GW, 554.9 cm/GW, 193.3 cm/GW and 117.1 cm/GW, respectively. The nonlinear performance of GOZS is 5–22 times higher than that of pure GO and ZnS, making it a potential optical limiting material. These results may be useful to design GOZS composites with better OL properties.

This special issue combines 13 invited and 35 contributed papers, offering a unique perspective on the most recent developments in integrated photonics over the last few years. The invited papers, authored by world-renowned research groups and promising scientists from all over the world, present extended reviews on recent progresses and significant perspectives on future research directions. Heterogeneous integration of dissimilar materials for integrated photonics remains one of the most active and promising areas of research, with both traditional semiconductor materials such as amorphous Si, germanium, and III-V quantum dots on silicon, as well as emerging materials such as thin film lithium niobate, nitride, silicon carbide, diamond, etc. Device structures are being explored for new functional applications, from traditional Datacom/telecom to optical, RF and nonlinear signal processing, nonreciprocal optics, midwave infrared sensing, etc. Integration schemes and system architecutures are being pursued for quantum computing, signal processing, machine learning, energy efficient neuromorphic computing, etc.

Objective Carbon monoxide (CO) releasing molecule (CORM)-3, a water-soluble CORM, has protective effects against inflammatory and ischemia/reperfusion injury. We determined the effect of CORM-3 against neuronal pyroptosis in a model of hemorrhagic shock and resuscitation (HSR) in rats via mitochondrial regulation. Methods Rats were treated with CORM-3 (4 mg/kg) in vitro after HSR. We measured cortical CO content 3–24 h after HSR; assessed neuronal pyroptosis, mitochondrial morphology, ROS production, and mitochondrial membrane potential at 12 h after HSR; and evaluated brain magnetic resonance imaging at 24 h after HSR and learning ability 30 days after HSR. We also measured soluble guanylate-cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signaling pathway activity using a blocker of sGC, NS2028, and 125 I-cGMP assay. Results Among rats that underwent HSR, CORM-3-treated rats had more CO in the cortical tissue than sham- and iCORM-3-treated rats. CORM-3-treated rats had significantly less neuronal pyroptosis in the cortical tissue; higher sGC activity and cGMP content; lower ROS production; better mitochondrial morphology, function, and membrane potential; and enhanced learning/memory ability than HSR-treated rats. However, these neuroprotective effects of CORM-3 were partially inhibited by NS2028. Conclusion CORM-3 may alleviate neuronal pyroptosis and improve neurological recovery in HSR through mitochondrial regulation mediated by the sGC–cGMP pathway. Thus, CO administration could be a promising therapeutic strategy for hemorrhagic shock.

In this work, we show how domain-engineered lithium niobate can be used to selectively dope monolayer molybdenum selenide (MoSe2) and tungsten selenide (WSe2) and demonstrate that these ferroelectric domains can significantly enhance or inhibit photoluminescence (PL), with the most dramatic modulation occurring at the heterojunction interface between two domains. A micro-PL and Raman system is used to obtain spatially resolved images of the differently doped transition metal dichalcogenides (TMDs). The domain-inverted lithium niobate causes changes in the TMDs due to electrostatic doping as a result of the remnant polarization from the substrate. Moreover, the differently doped TMDs (n-type MoSe2 and p-type WSe2) exhibit opposite PL modulation. Distinct oppositely charged domains were obtained with a 9-fold PL enhancement for the same single MoSe2 sheet when adhered to the positive (P+) and negative (P–) domains. This sharp PL modulation on the ferroelectric domain results from different free electron or ...

© 2018 American Chemical Society. Semiconductor nanowire (NW) lasers have attracted considerable research effort given their excellent promise for nanoscale photonic sources. However, NW lasers currently exhibit poor directionality and high threshold gain, issues critically limiting their prospects for on-chip light sources with extremely reduced footprint and efficient power consumption. Here, we propose a new design and experimentally demonstrate a vertically emitting indium phosphide (InP) NW laser structure showing high emission directionality and reduced energy requirements for operation. The structure of the laser combines an InP NW integrated in a cat's eye (CE) antenna. Thanks to the antenna guidance with broken asymmetry, strong focusing ability, and high Q-factor, the designed InP CE-NW lasers exhibit a higher degree of polarization, narrower emission angle, enhanced internal quantum efficiency, and reduced lasing threshold. Hence, this NW laser-antenna system provides a very promising approach toward the achievement of high-performance nanoscale lasers, with excellent prospects for use as highly localized light sources in present and future integrated nanophotonics systems for applications in advanced sensing, high-resolution imaging, and quantum communications.

In this paper, we perform coupled optical and electrical simulation for core–shell junction GaAs nanowire array solar cells to obtain the important physical insights of how the cell efficiency is affected by various key parameters, including core–shell doping, junction position, carrier lifetime, and surface effect. Our study reveals that junction design in core–shell nanowires in terms of doping and geometry is largely restricted and affected by the small nanowire dimension, requiring different optimization from those of conventional planar solar cells. To take advantage of the radial p-n junction, high core and shell doping are essential to achieve effective radial carrier collection. Moreover, maintaining thin nanowire shell could effectively offset the detrimental surface effect for improved efficiency.

We report the growth of GaAs/AlGaAs core-shell nanowire ensembles grown on p- and n-doped GaAs substrate respectively and the fabrication of these nanowire photodetectors. The I-V characteristics and spectral response of both detectors were investigated by comparison.

Numerous studies have demonstrated the antioxidant effects of grape seed proanthocyanidin extract (GSPE). The generation of free radicals and the ensuing apoptosis may contribute to the pathogenesis of epilepsy; therefore, in the present study, we examined the effects of GSPE on cognitive impairment and neuronal damage induced by chronic seizures in rats. Seizures were induced by a daily intraperitoneal (i.p.) injection of pentylenetetrazole (PTZ; 35 mg/kg/day, 36 days). Two other groups were treated with GSPE (100 or 200 mg/kg/day, orally) for 24 days and then for 36 days prior to each PTZ injection. After the final PTZ injection, hippocampus-dependent spatial learning was assessed using the Morris water maze (MWM). The rats were then sacrificed for the measurement of hippocampal malondialdehyde (MDA, a measure of lipid peroxidation) and glutathione (GSH, a measure of endogenous antioxidant capacity) levels, and for the expression of pro-apoptotic factors [cytochrome c (Cyt c), caspase‑9 and caspase‑3]. The mitochondrial generation of reactive oxygen species (ROS), degree of mitochondrial swelling, neuronal damage and mitochondrial ultrastructure were also examined. Performance in the MWM was markedly impaired by PTZ-induced seizures, as evidenced by longer escape latencies during training and fewer platform crossings during the probe trial. This cognitive decline was accompanied by oxidative stress (MDA accumulation, ROS generation, reduced GSH activity), an increased expression of pro-apoptotic proteins, as well as damage to CA1 pyramidal neurons and the mitochondria. Pre-treatment with GSPE dose‑dependently reversed PTZ-induced impaired performance in the MWM, oxidative stress, mitochondrial ROS generation, the expression of pro-apoptotic proteins and neuronal and mitochondrial damage. Thus, GSPE may reverse the hippocampal dysfunction induced by chronic seizures, by reducing oxidative stress and preserving mitochondrial function.

Surface interaction is extremely important to both fundamental research and practical application. Physisorption can induce shape and structural distortion (i.e. conformational changes) in macromolecular and biomolecular adsorbates, but such phenomenon has rarely been observed on adsorbents. Here, we demonstrate theoretically and experimentally that atomically thin boron nitride (BN) nanosheets as an adsorbent experience conformational changes upon surface adsorption of molecules, increasing adsorption energy and efficiency. The study not only provides new perspectives on the strong adsorption capability of BN nanosheets and many other two-dimensional nanomaterials but also opens up possibilities for many novel applications. For example, we demonstrate that BN nanosheets with the same surface area as bulk hBN particles are more effective in purification and sensing.

Copper nanoparticles (Cu NPs) have attracted tremendous interest in recent years in the field of printable electronics due to their low cost and high conductive properties. In this study, copper nanoparticles were synthesized via a polyol method by reducing cupric nitrate trihydrate with hydrazine hydrate in the presence of PVP as protective agent. Collide of Cu NPs was obtained after three times of sedimentation by acetone. Suspension for conductive ink was then prepared by adding some amount of solutions and additives followed by parameters adjusting. Sheet resistance of the Cu NPs films coated on a glass substrate could be reduced to 750 mΩ/□ after heating at 300°C for 1h in vacuum.

Aims: To analyze the incidence of and risk factors for post-pancreatoduodenectomy (PD) hemorrhage (PPH) and to evaluate the outcomes of reinterventions for PPH. Methods: All PDs between January 2009 and December 2014 were retrospectively evaluated. PPH was evaluated according to the criteria of the International Study Group of Pancreatic Surgery. Both univariate and multivariate analyses of risk factors for PPH and mortality were performed. Reinterventions were also evaluated. Results: Of the 1,056 PDs during the study period, 78 (7.4%) developed PPH, including 36 with grade B and 42 with grade C. Of these 78 patients, 24 (30.8%) died of PPH-related causes. Multivariate analysis showed that older age, higher total bilirubin concentration, and postoperative pancreatic fistula (POPF) were independent risk factors for PPH. Patients who died of PPH were significantly older and had lower preoperative hemoglobin and albumin concentrations than patients who did not die of PPH. Of the 78 patients with PPH, 58 underwent reintervention, including 27 who underwent angiography, 24 who underwent endoscopy, 24 who underwent re-laparotomy, and 15 who underwent more than one reintervention. Conclusions: Older age, total bilirubin, and POPF are independent risk factors for PPH. Higher mortality are associated with advanced PPH and poor nutritional conditions.

Proton implantation and rapid thermal annealing were used to tune the infrared spectral response of quantum-well infrared photodetectors (QWIP) by up to 1.4 μm. Multiple proton implants at energies between 200 and 420 keV were used to create homogeneous quantum-well intermixing throughout the device’s multiple-quantum-well structure. Photoluminescence and spectral response measurements were used to study the effect of proton implantation on QWIPs for a series of doses up to 3.5×1015 protons cm−2. By using a mask during implantation, a method of constructing a color sensitive array is proposed.

We have used photoluminescence up conversion to study the carrier capture times into intermixed InGaAs/GaAs quantum wells. We have found that the capture into the intermixed wells is markedly faster than capture into the reference (unintermixed) quantum wells. The reasons for the significant reduction in the capture time is related to the shape of the intermixed quantum well. Such a reduction in the capture time is beneficial both in terms of the quantum efficiency and the frequency response of intermixed optoelectronic devices.

Conductive ink, especially the nano-silver ink is becoming more and more popular in printable electronic field. In order to synthesize high concentration, stable nano-silver colloid, liquid chemical reduction is used and different ratios of PVP to silver nitrate are studied. After precise adjustments of the parameters, colloid with silver content of wt7.8% is obtained. Particle size distribution, UV-Vis spectra, thermo gravimetric analysis and SEM images are conducted to characterize the silver particles. The results show that when molar ratio of PVP to silver nitrate is 0.6, the average particle size is 170nm and some deposit can be seen, while the ratio increases to 1.5, the size decreases to 68nm, and the residue quality of the silver colloid showed in the TG analysis is 7.88%. After aging for 1 month, the colloid is still stable and the color keeps to the original dark green. When the ratio continues increasing to 2.5, particle size becomes 112nm and some larger particles beyond 3μm can be observed.

Silver (Ag) deposition was performed on a polyaniline-precoated surface for textile metallization. Polyaniline was utilized as an intermediate layer on fabrics to facilitate Ag formation. Inductivily coupled plasma atomic emission spectgrometry (ICP-AES) was used to monitor the content of metallic elements on Ag-laden polyaniline layers prepared under different conditions of polyaniline fomation. The surface modification of the samples before and after Ag plating was characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and atomic force microscopy (AFM).

According to the Shockley–Queisser limit, the maximum achievable efficiency for a single junction solar cell is ~33.2% which corresponds to a bandgap (E g) of 1.35 eV (InP). However, the maximum reported efficiency for InP solar cells remain at 24.2% ± 0.5%, that is >25% below the standard Shockley–Queisser limit. Through a wide range of simulations, we propose a new device structure, ITO/ ZnO/i-InP/p+ InP (p-i-ZnO-ITO) which might be able to fill this efficiency gap. Our simulation shows that the use of a thin ZnO layer improves passivation of the underlying i-InP layer and provides electron selectivity leading to significantly higher efficiency when compared to their n+/i/p+ homojunction counterpart. As a proof-of-concept, we fabricated ITO/ZnO/i-InP solar cell on a p+ InP substrate and achieved an open-circuit voltage (V oc) and efficiency as high as 819 mV and 18.12%, respectively, along with ~90% internal quantum efficiency. The entire device fabrication process consists of four simple steps which are highly controllable and reproducible. This work lays the foundation for a new generation of thin film InP solar cells based solely on carrier selective heterojunctions without the requirement of extrinsic doping and can be particularly useful when p- and n-doping are challenging as in the case of III–V nanostructures.

This paper reports the experimental work on the characterization of quantum dot-in-well (DWELL) solar cell grown by metal-organic chemical vapor deposition (MOCVD) without employing any post-growing optimization like antireflection coating and metal grid. The structure of the 10-layer DWELL solar cells is studied by cross-sectional transmission electron microscopy (TEM). Room temperature photoluminescence (PL) spectra show strong quantization at 1178.5 nm with a linewidth of 79.9 nm. External quantum efficiency spectra show enhancement in the spectral response of the photocurrent with respect to the reference quantum dot cell (without DWELL structure). In spite of the reduction in conversion efficiency due to poor collection of current in external circuit compared to reference quantum dot cell it show the improvement in open circuit voltage.

Over 1.0 mm boron nitride nanotubes (BNNTs) were successfully synthesized by an optimized ball milling and annealing method. The annealing temperature of 1100 °C is crucial for the growth of the long BNNTs because at this temperature there is a fast nitrogen dissolution rate in Fe and the B/N ratio in Fe is 1. Such long BNNTs enable a reliable single tube configuration for electrical property characterization and consequently the average resistivity of the long BNNTs is determined to be 7.1 ± 0.9 × 104 Ω cm. Therefore, these BNNTs are promising insulators for three dimensional microelectromechanical system.

Tunable electronic properties of nanotubes are an essential requirement for building nanotube circuits and devices. We have produced BN nanotube films with controlled electric conductivities by Au doping. The Au -doped BN nanotube films have been found to exhibit from semiconducting to metallic behavior under different Au contents. Both experimental and computing simulation studies reveal that the conductivities of the doped film are improved by the incorporation of Au atoms into nanotube walls. The doped BN nanotubes and films are expected to have potential applications in catalysts, sensors and nanoelectronics.

© 2014 IEEE. We demonstrate an optical method to evaluate the doping concentration, internal quantum efficiency (IQE) and non-radiative lifetime of semiconductor nanowires, through power dependent photoluminescence (PL) and time resolved PL (TRPL) measurement. Combining this method with standard PL and time resolved spectrum, we analyse the quality, band structure and doping distribution of Si doped InP nanowires. The doping result is correlated with electrical measurements of single nano wire device.

The anisotropic nature of the new two-dimensional (2D) material phosphorene, in contrast to other 2D materials such as graphene and transition metal dichalcogenide (TMD) semiconductors, allows excitons to be confined in a quasi-one-dimensional (1D) space predicted in theory, leading to remarkable phenomena arising from the reduced dimensionality and screening. Here, we report a trion (charged exciton) binding energy of 190 meV in few-layer phosphorene at room temperature, which is nearly one to two orders of magnitude larger than those in 2D TMD semiconductors (20-30 meV) and quasi-2D quantum wells (1-5 meV). Such a large binding energy has only been observed in truly 1D materials such as carbon nanotubes, whose optoelectronic applications have been severely hurdled by their intrinsically small optical cross-sections. Phosphorene offers an elegant way to overcome this hurdle by enabling quasi-1D excitonic and trionic behaviors in a large 2D area, allowing optoelectronic integration. We experimentally validated the quasi-1D nature of excitonic and trionic dynamics in phospherene by demonstrating completely linearly polarized light emission from excitons and trions. The implications of the extraordinarily large trion binding energy in a higher-than-one-dimensional material are far-reaching. It provides a room-temperature 2D platform to observe the fundamental many-body interactions in the quasi-1D region. The strong photoluminescence emission in phosphorene has been electrically tuned over a large spectral range at room temperature, which opens a new route for tunable light sources.

J. Wong-Leung, P. N. K. Deenapanray, and H. H. Tan acknowledge the fellowships awarded by the Australian Research Council.

© 2014 IEEE. Photoconductive terahertz detectors based on single GaAs/AlGaAs core-shell nanowire have been designed and fabricated. The devices were characterised in a terahertz time-domain spectroscopy system, showing excellent sensitivity comparable to the standard bulk ion-implanted InP receiver, with a detection bandwidth of 0.1 ∼ 0.6 THz. Finite-difference time-domain simulations were performed to understand the origin of the narrow bandwidth of current detectors as well as optimize antenna designs to improve detector performance.

Lung cancer is one of the most common cancers and is the leading cause of death worldwide. Platinum-based chemotherapy is the main treatment method in lung cancer patients. Our previous studies indicated that single nucleotide polymorphisms (SNPs) in some transporter genes played important role in platinum-based chemotherapy efficacy. The aim of this study was to investigate the association of SNPs in transporter genes and platinum-based chemotherapy efficacy. The main polymorphisms on transporters OCT2, LRP, AQP2, AQP9 and TMEM205 genes were genotyped in 338 lung cancer patients. The rs195854 in genotypic model, rs896412 in genotypic and recessive models for all subjects showed significant association with chemotherapy response. In stratification analysis, TMEM205 rs896412, OCT2 rs1869641 and rs195854, AQP9 rs1516400 and AQP2 rs7314734 showed significant relation to chemotherapy response. In conclusion, the genetic polymorphisms in OCT2, AQP2, AQP9 and TMEM205 may contribute to chemotherapy response in lung cancer patients.

Numerical simulation of GaAs core-shell nanowire array solar cells is performed to investigate the effects of junction design in terms of doping and position, surface condition and carrier lifetime on photovoltaic efficiencies.

Proton irradiation with subsequent rapid thermal annealing was used to investigate intermixing of InGaAs/GaAs and InGaAs/AlGaAs quantum wells. Large photoluminescence ~PL! energy shifts were observed in both materials. Comparatively, InGaAs/AlGaAs samples showed larger PL energy shifts than InGaAs/GaAs samples because of the presence of Al in the barriers and also better recovery of PL intensities, which is mainly due to dynamic annealing effects in AlGaAs during irradiation. Based on this, InGaAs/AlGaAs quantum-well lasers were fabricated and up to 49.3-nm-emission wavelength shift was observed in the proton-irradiated laser with no significant degradation in device characteristics. © 1999 American Institute of Physics. @S0021-8979~99!09609-7#

We report the growth by low-pressure metal-organic chemical vapor deposition, fabrication, and characterization of ten-layer In/sub 0.5/Ga/sub 0.5/As/GaAs quantum dot infrared photodetectors. Normal incidence photoresponse of the detector was obtained at 5.9 /spl mu/m. The 77-K peak responsivity was 5.6 mA/W with the detectivity D/sup */ of 1.2/spl times/10/sup 9/ cm/spl middot/Hz/sup 1/2//W at the bias of 0.4 V.

Devices based upon semiconductor nanowires provide many well-known advantages for next-generation photovoltaics, however, limited experimental techniques exist to determine essential electrical parameters within these devices. We present a novel application of a technique based upon two-photon induced photocurrent that provides a submicrometer resolution, three-dimensional reconstruction of photovoltaic parameters. This tool is used to characterize two GaAs nanowire-based devices, revealing the detail of current generation and collection, providing a path toward achieving the promise of nanowire-based photovoltaic devices.

Thermal-stress controlled interdiffusion in InGaAsN/GaAs quantum dots (QDs) has been studied by deposition of titanium oxide (TiO2) layers combined with rapid thermal annealing. Without TiO2 cap layers, blueshifting of the band gap from 1.033 to 1.180 eV at 77 K has been observed after annealing at 850 °C for 30 s due to the thermal interdiffusion. The thermal interdiffusion has been effectively suppressed by depositing TiO2 layers on the samples without degrading the photoluminescence properties. By a combination of annealing temperature and TiO2 thickness, controlled blueshifting of the band gap has been achieved. We suggest that the mechanism of suppression of thermal interdiffusion is the thermal stress imposed on the QD structure generated by TiO2 layers during annealing.

Semiconductor nanowire solar cells (NWSCs) have attracted significant interests owning to their potential in the applications of high-performance solar cells. Here, we report improved GaAs solar cell performance using a high-quality AlGaAs shell for surface passivation. The device exhibits an open-circuit voltage (Voc) of 0.70V, a short-circuit current density (Jsc) of 9.79 mA/cm2, a fill factor (FF) of 0.52, and a total power conversion efficiency (η) of 4.22%. This work suggests a promising route to optimize NWSCs. © 2012 IEEE.

The enhancement in short-circuit current density (Jsc) provided by a TiO2 diffraction grating composed of rectangular strips at the rear of an In0.21Ga0.79As-GaAs quantum well solar cell (QWSC) is investigated using finite-difference time-domain (FDTD) simulations. Optimisation of the grating height, periodicity and fill-factor yielded an enhancement of 5.3% in Jsc over the reference cell.

In this work, we report the use of dielectric capping layer of TiO 2 to selectively suppress thermal interdiffusion of an InGaAs/GaAs quantum well laser structure. Large differential wavelength shift of ∼ 25nm has been obtained across the same wafer between the uncapped and capped regions which is promising for achieving monolithic integration of multi-section semiconductor laser consisting of a gain, a phase and a passive waveguide sections.

N-type silicon modulation doping was introduced into the barrier layers of InGaAs/GaAs quantum dot solar cells (QDSC) at two different doping concentrations. An increased energy conversion efficiency of 8.91 % was obtained for the modulation doped device compared to 6.95 % of the undoped sample due to the additional electron population in the active structure.

In this work, titanium dioxide (TiO2) film was deposited onto the In0.5Ga0.5As/GaAs quantum-dot structure by electron-beam evaporation to investigate its effect on interdiffusion. A large redshifted and broadened spectrum from the dot emission was observed compared with that from the uncapped (but annealed) reference sample, indicating the suppression of thermal interdiffusion due to TiO2 deposition. The structure was also capped with a silicon dioxide (SiO2) single layer or SiO2/TiO2 bilayer with the thickness of SiO2 varied from ∼6 to ∼145 nm. In the former case, an increased amount of impurity-free vacancy disordering (IFVD) was introduced with the increase of SiO2 thickness due to the enhanced Ga outdiffusion into the film. With TiO2 deposited on top, IFVD and thermal interdiffusion were suppressed to different extents with the variation of SiO2 thickness. To explain the suppression of interdiffusion, thermal stress introduced by the large thermal expansion coefficient of TiO2 (when compared with GaAs...

III–V semiconductors like GaAs and InGaN are very promising candidates for solar cells. While GaAs has near-ideal bandgap to reach the maximum possible efficiency limit for single junction solar cells, InGaN provides the ability to tune the bandgap of absorbing layers over a wide energy range. Since III–V semiconductors are mostly direct bandgap semiconductors, they are also very strong absorbers of light. Currently novel solar cell designs based on nanostructured absorbers like quantum dots1,2 or nanowires are under investigation to demonstrate high efficiency solar cells.

A single GaAs nanowire (NW) photodetector (PD) is fabricated based on the back-to-back Schottky diode structure. Optoelectronic properties are characterized by measuring device photocurrent, and also the spectral response, which indicates our device is very sensitive and applicable as a PD. © 2012 IEEE.

Two of the authors (P.N.K.D. and H.H.T.) gratefully acknowledge financial support by the Australian Research Council.

One of the authors (H.H.T.) acknowledges a fellowship awarded to him by the Australian Research Council.

We demonstrate that plasmonic light trapping effect can be used to improve all the main device characteristics of self-assembled InGaAs/GaAs quantum dot solar cell. The underlying physical processes of carrier occupation, transportation, and recombination within the plasmonic quantum dot solar cells will be discussed.

An analysis of the temperature dependent dark current and spectral response characteristics of an In 0.5 Ga 0.5 As/GaAs quantum dot solar cell has been performed to determine the dominant physical processes that lead to a reduction of the open circuit voltage compared with reference single junction GaAs solar cells.

We have improved the stability and performance of terahertz (THz) photoconductive (Auston) switches using a combination of (NH4) 2S surface passivation (SP) and silicon nitride (Si3 N4) encapsulation. The influences of SP and encapsulation on the ultrafast electron dynamics in GaAs were examined using THz emission spectroscopy and optical pumpTHz probe spectroscopy. The power of THz radiation from the surface of photoexcited GaAs increased by a factor of 5 after passivation and encapsulation, while the process lengthened the trapping time for photoexcited charge carriers. By fabricating and assessing the performance of photoconductive switches, we found that passivation and encapsulation increased the average THz power generated fourfold. © 2010 IEEE.

Quantum dot intermixing is a post-growth approach to tuning optoelectronic devices. SiO 2 capping layers can enhance these effects through impurityfree vacancy disordering, whereas TiO 2 caps can decrease intermixing. In this study, multi-colour quantum dot infrared photodetectors were fabricated through selective intermixing and four different encapsulants were investigated.

In this work, controlled band gap modifications in AlInGaAs/InGaAs quantum well structures using different encapsulating layers are studied and compared. X-ray photoelectron spectroscopy was used to investigate the interfacial reaction between the quantum well structure and dielectric capping layer.

In this article, we show that the introduction of a spiral waveguide to a GaAs microdisk that works both as a waveguide and circular Bragg reflector can improve coupling efficiency to almost 90%. The same structure with the addition of a taper can couple up to 80% of the generated power into a slot waveguide.

We investigated the temperature effect on the electrical properties of an In 0.5 Ga 0.5 As/GaAs QD solar cell, leading to a better understanding of the basic cell characteristics influenced by QD incorporation which is of great importance for future design of high efficiency QD solar cells.

The quality of spin-on silica films prebaked at different temperatures has been studied using Fourier transform infrared spectroscopy, spectroscopic ellipsometry, and P-etch [HF(40%):HNO3(70%):H2O=3:2:60] measurements. Low-temperature photoluminescence (PL) was performed on GaAs/AlGaAs quantum-well (QW) structures encapsulated by the same films. For all the prebaked films, not only the Si–O–Si peaks, but also OH-related peaks were detected in the IR spectra. After annealing at 950 °C for 60 s, almost all OH-related peaks disappeared. Spectroscopic ellipsometry modeling and P-etch measurements showed that the porosity of high-temperature (>300 °C) baked samples was similar, and was significantly higher than the low-temperature (210 °C) baked sample. The same trend was observed in the PL energy shifts from the GaAs/AlGaAs QWs, indicating a direct correlation between the film quality and quantum-well intermixing.