Energy band adjustment of 808 nm GaAs laser power converters via gradient doping

The gradient doping regions were employed in the emitter layer and the base layer of GaAs based laser power converters(LPCs).Silvaco TCAD was used to numerically simulate the linear gradient doping and exponential gradient doping structure,and analyze the transport process of photogenerated carriers.Energy band adjustment via gradient doping improved the separation and transport efficiency of photogenerated carriers and reduced the total recombination rate of GaAs LPCs.Compared with traditional structure of LPCs,the photoelectric conversion efficiency of LPCs with linear and exponential gradient doping structure were improved from 52.7%to 57.2%and 57.7%,respectively,under 808 nm laser light at the power density of 1 W/cm^(2).

America's Journey to Energy Independence and Its Revelation on China's Energy Supply Security

Ever since 2005, the US' shale oil and gas production growth and effective adjustment of domestic energy consumption mix have made it possible for the country to be less dependent upon imported energy and gain energy independence. What should we learn from it to guarantee energy supply security? This paper tried to answer the question.

Impact of energy structure adjustment on air quality:a case study in Beijing,China

Energy consumption is a major cause of air pollution in Beijing,and the adjustment of the energy structure is of strategic importance to the reduction of carbon intensity and the improvement of air quality.In this paper,we explored the future trend of energy structure adjustment in Beijing till 2020,designed five energy scenarios focusing on the fuel substitution in power plants and heating sectors,established emission inventories,and utilized the Mesoscale Modeling System Generation 5(MM5)and the Models-3/Community Multiscale Air Quality Model(CMAQ)to evaluate the impact of these measures on air quality.By implementing this systematic energy structure adjustment,the emissions of PM_(10),PM_(2.5),SO_(2),NO_(x),and non-methane volatile organic compounds(NMVOCs)will decrease distinctly by 34.0%,53.2%,78.3%,47.0%,and 30.6%respectively in the most coalintensive scenario of 2020 compared with 2005.Correspondingly,MM5-Models-3/CMAQ simulations indicate significant reduction in the concentrations of major pollutants,implying that energy structure adjustment can play an important role in improving Beijing’s air quality.By fuel substitution for power plants and heating boilers,PM_(10),PM_(2.5),SO_(2),NO_(x),and NMVOCs will be reduced further,but slightly by 1.7%,4.5%,11.4%,13.5%,and 8.8%respectively in the least coal-intensive scenario.The air quality impacts of different scenarios in 2020 resemble each other,indicating that the potential of air quality improvement due to structure adjustment in power plants and heating sectors is limited.However,the CO_(2) emission is 10.0%lower in the least coal-intensive scenario than in the most coal-intensive one,contributing to Beijing’s ambition to build a low carbon city.Except for energy structure adjustment,it is necessary to take further measures to ensure the attainment of air quality standards.

Influence of energy bandwidth of pink beam on small angle X-ray scattering

Background Compared with the traditional monochromatic synchrotron radiation beam,a pink beam is a quasimonochromatic beam which can be obtained by screening a harmonic of the undulator.The energy bandwidth(E/E)of a pink beam is about 10−2.Despite the intensity gain from the quasi-monochromatic beam,the decrease in the energy resolution will lead the collected data to be smeared.Purpose To study the influence of the energy bandwidth on the small angle X-ray scattering(SAXS)by experiments and verify the feasibility of SAXS with a pink beam.Method Firstly,the influence of different energy bandwidths on SAXS has been studied by simulation and experiment.Then,TEM tests have been performed and compared with the experimental results.Result It has been shown that the scattering curves deviate slightly from the traditional monochromatic ones.This deviation does not influence the data processing for the maximum deviation of the results is just less than 2%.In return,the gain in the intensity(one to two orders of magnitude)makes the pink beam very important for the time-resolved SAXS.Further,the results of TEM and SAXS have shown an excellent agreement.Conclusion Thiswork proves that the pink beam could be used for SAXS directly without a desmearing procedure.Benefiting from the increase in the beam intensity,the exposure time can be greatly shortened,thus enhancing the utilization efficiency of the synchrotron radiation.