Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well solar cells

Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well(MQW) solar cells are investigated. It is found that due to the reduction of piezoelectric polarization and the enhancement of tunneling transport of photo-generated carriers in MQWs, the external quantum efficiency(EQE) of the solar cells increases in a low energy spectral range(λ 370 nm) when the barrier thickness value decreases from 15 nm to 7.5 nm. But the EQE decreases abruptly when the barrier thickness value decreases down to 3.75 nm. The reasons for these experimental results are analyzed. We are aware that the reduction of depletion width in MQW region, caused by the high resistivity of the p-type GaN layer may be the main reason for the abnormally low EQE value at long wavelengths(λ 370 nm).     

Novel electrospun SnO2@carbon nanofibers as high performance anodes for lithium‐ion batteries

SnO₂@carbon (SnO₂@C) nanofibers (NFs) have been prepared by electrospinning method and evaluated as anodes in lithium‐ion battery half cells. XRD were carried out to provide further information about the structure of the as‐prepared NFs, and all the peaks can be readily indexed to the rutile phase SnO₂ (JCPDS No. 41–1445). Electrochemical characterization by galvanostatic charge‐discharge tests shows that the NF anodes have first discharge capacities of 1375.5 mA h g⁻¹ at 80 mA g⁻¹current density. This excellent Li‐ion storage capability of SnO₂ NFs is probably resulting from protection of amorphous carbon and the synergy arising from that the ultrafine SnO₂ particles embedded in the carbon nanofiber (CNF) matrix: the nanometer‐sized SnO₂@C NFs can provide not only negligible diffusion times of ions thus faster phase transitions but also enough space to buffer the volume changes during the lithium insertion and extraction reactions. The highly dispersed NFs are expected to be applied as attractive anodes for lithium‐ion batteries.     

Epitaxial Bi2Sr2CuOy thin films as p-type transparent conductors

Development of p-type transparent conducting thin films is tireless due to the trade-off issue between optical transparency and conductivity. The rarely concerned low normal state resistance makes Bi-based superconducting cuprates the potential hole-type transparent conductors, which have been realized in Bi₂Sr₂CaCu₂O_y thin films. In this study, epitaxial superconducting Bi₂Sr₂CuO_y and Bi₂Sr_1.8Nd_0.2CuO_y thin films with superior normal state conductivity are proposed as p-type transparent conductors. It is found that the Bi₂Sr_1.8Nd_0.2CuO_y thin film with thickness 15 nm shows an average visible transmittance of 65% and room-temperature sheet resistance of 650 Ω/sq. The results further demonstrate that Bi-based cuprate superconductors can be regarded as potential p-type transparent conductors for future optoelectronic applications.     

第一性原理研究Te-N共掺p型ZnO

采用基于密度泛函理论的第一性原理赝势法对Te-N共掺杂ZnO体系的晶格结构、 杂质态密度和电子结构进行了理论分析.研究表明, N掺杂引起晶格收缩,而Te的掺入引起晶格膨胀, 从而减小晶格应力促进N的掺杂,并且Te由于电负性小于O而带正电, Te在ZnO中作为等电子施主而存在.研究发现, N掺杂体系中在费米能级附件形成窄的深受主能级, 而Te-N共掺体系中, N杂质带变宽,空穴更加离域,同时,空穴有效质量变小,受主能级变浅, 更有利于实现p型特性.因此, Te-N共掺有望成为一种更为有效的p型掺杂手段.     

有机-ZnO纳米线混合光电二极管特性

采用水热法制备了1维ZnO纳米线,并通过改变ZnO纳米线的取向（横向和竖直）和不同的P型半导体材料,制备了不同的有机-ZnO纳米线混合光电二极管。通过改变光照与非光照的条件下并在光照条件下改变光电二极管与光源的距离,对所制备的光电二极管的相关特性进行研究。结果表明:采用水热技术能够制备高质量的ZnO纳米线;当光电二极管两端通正向电压时,光照时的电流大于非光照时的电流,当通反向电压时,结果则相反;同时,光电流还与光照强度有关,光照强度越大,光电流越大。     

电合成2,2-二羟甲基丙酸

制备Ti/SnO2+Sb2O4/PbO2电极,电极的组分及其价态由XRD和XPS表征;该电极可将2,2-二羟甲基丙醛直接电合成2,2-二羟甲基丙酸.应用高效液相色谱分析原料和产物,电化学方法研究电合成影响因素,包括:2,2-二羟甲基丙醛浓度、溶液pH值、反应温度和氧化电位等.在优化条件下(pH=1,C醛=0.10 mol.L-1,t=15℃,E=1.8 V)电合成2,2-二羟甲基丙酸的转化率为58%,选择性36%,电流效率28%.本法为该产物的合成提供了一种新的途径.     

磷扩散法制备高掺磷p型ZnO薄膜的磁控溅射工艺的探索

在前期通过n+-Si衬底中的磷向沉积于其上面的ZnO薄膜的扩散制备高掺磷p型ZnO薄膜的研究基础上,探索了较有普遍应用意义的扩散法制备p型ZnO薄膜的磁控溅射工艺.结果表明,当磁控溅射的氧氩质量流量比与衬底温度满足特定的低阶指数函数的匹配关系时,所制备的ZnO薄膜为p型,而且薄膜中磷原子的深度分布是均匀的;另外,这种薄膜的厚度随着氧氩流量比的增加而减小,而薄膜中氧锌原子浓度比都大于1,比值大小与氧氩质量流量比和衬底温度有关.     

关于B值行独立随机元阵列部分和的完全收敛性的注记

讨论了p型Banach空间（1≤p≤2）下,B值行独立随机元阵列部分和的完全收敛性,得到了几个充分条件的结果,它们是实值随机变量阵列完全收敛性的推广。     

Sb掺杂SnO2纳米粉体的结晶行为和电学性能

掺锑;Sb掺杂SnO2纳米粉体的结晶行为和电学性能