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Using activated carbon (AC) with nano- lithium iron phosphate (LiFePO 4 ) as the positive and hard carbon (HC) as the negative, this type lithium-ion capacitor (LIC) has the inherent advantages in rate characteristics, cycle life and chemical stability, which is more suitable for rail transit application. As an indicator of capacitor available energy, state of energy (SOE) is of great importance to estimate. However, most of the models utilized in the literature concerning state estimation of LIC become problematic for outlining the characteristics without considering wide current magnification. In this work, a method, which is considering wide current magnification, is proposed for state of energy estimation of LIC.

Silicon film as a surface passivation layer is reported to reduce surface recombination on silicon nanowires (SiNWs) and thus enable to improve SiNW solar cell (SC) performance. A question yet to be answered regards the link between the silicon film assets and the solar cell performances. We investigated the effect of the properties of silicon films on the SiNWs SC performances by adjusting hydrogen dilution. Our results showed that the open-circuit voltage (Voc) and short-circuit current density (Jsc) of SiNWs SC increase until hydrogen dilution 10 and then decrease. An open-circuit voltage of 0.397 V and short-circuit current density of 18.42 mA/cm2 are achieved at optimized hydrogen dilution. Based on the analysis of silicon film properties we proposed that the increase of defect density with hydrogen dilution was the main cause for the deterioration of SiNWs SC performance.

High power and high brightness InP based lasers around 2 µm are attractive for many applications due to their intrinsic compatibility with photonic integrated circuits. However, high output power and low lateral divergence are difficult to be realized simultaneously with the traditional ridge waveguide structure. In this paper, we demonstrate significantly enhanced performance of 1.96 µm InP based InGaAs quantum well lasers by tapered waveguide structures. The double-channel waveguide laser with a straight waveguide section and a small-angle tapered optical amplifier section showed fundamental transverse mode lasing with an excellent beam quality. In agreement with our designed waveguide structures, the devices’ lateral divergence is remarkably reduced. For the device with a 3° tapered angle, the narrowest full width at half maximum (FWHM) of 8.2° of the far-field distribution is realized and the continuous-wave output power, measured at 25 °C, is increased up to 40 mW, which is much higher than the 12 mW of the laser with only a straight ridge waveguide.

To heteroepitaxally grow the crystalline cubic-GaN (c-GaN) film on the substrates with large lattice mismatch is basically important for fabricating the blue or ultra-violet laser diodes based on cubic group III nitride materials. We have obtained the crystalline c-GaN film and the heteroepitaxial interface between c-Gan and GaAs(001) substrate by the ECR Plasma-Assisted Metal Organic Chemical Vapor Deposition (PA-MOCVD) under low-pressure and low-temperature (∼600°C) on a homemade ECR-plasma Semiconductor Processing Device (ESPD). In order to decrease the growth temperature, the ECR plasma source was adopted as the activated nitrogen source, therefore the working pressure of MOCVD was decreased down to the region less than 1 Pa. To eliminate the damages from energetic ions of current plasma source, a Multi-cusp cavity-coupling ECR Plasma source (MEP) was selected to use in our experiment. To decrease the strain and dislocations induced from the large lattice mismatch between c-GaN and GaAs substrate, the plasma pretreatment procedure i.e., the initial growth technique was investigated. The experiment arrangements, the characteristics of plasma and the growth procedure, the characteristics of c-GaN film and interface between c-GaN and GaAs(001), and the roles of ECR plasma are described in this contribution.

GaAs grown under Ga-rich conditions often contains two dominant deep levels, sometimes referred to as the A and B levels. The authors have investigated the electronic properties of these levels in n-type and p-type material. The apparent activation energies for thermal hole emission were measured over eight orders of magnitude of thermal emission rate, and found to be 0.40 eV for level A and 0.70 eV for level B after the T2 correction. All four optical cross sections have been determined. The thresholds for electron excitation are 1.15 and 0.90 eV for the A and B levels, respectively, at 80K. A photocapacitance method is used to demonstrate that the two levels are coupled and thus due to one single defect. The electronic properties, in combination with the conditions under which the defect is formed, lead to the suggestion that the defect may be the GaAs antisite.

Our investigations of one iron- and two copper-related deep acceptor levels in the semiconductor alloy AlGaAs show that the opticalthreshold energies have the same linear composition dependence for all three levels. The particular nonexponential transient behaviour for thermal emission of carriers can be explained by a model in which the energy levels are broadened. A broadening mechanism due to random alloying is suggested.

A photocapacitance method was used to monitor the time dependences of the occupation numbers for the gold‐related donor and acceptor in silicon during optical excitation. The experimental data give strong evidence that the donor level corresponds to the +/0 transition and the acceptor to the 0/− transition for one single defect.

Concentration measurements using the electron paramagnetic resonance (EPR) signature of the Ni3+ (3d7) state in GaP have been compared with thermal emission and photocapacitance data measured on the same samples. These data combined with EPR photo-quenching measurements provide a definitive assignment of a state with a thermal activation energy for hole emission of 510 meV to the Ni3+ to Ni2+ transition. The optical threshold for the same transition is 520 meV and the cross section for thermal capture of a hole into Ni2+ is 1.3*10-16 cm2 at 240K.