Cadmium sulfide passivation of InGaAs/InP mesa p-i-n photodiodes

A cadmium sulfide (CdS) passivation process was demonstrated for the first time on InGaAs/InP p-i-n mesa photodetectors. The passivated devices produced lower reverse bias leakage currents in comparison to devices that received only a thermally deposited SiO₂ film. The subsequent deposition of SiO₂ on the passivated devices produced virtually no change to the aforementioned leakage currents even after undergoing a 3-h, 300°C thermal treatment. In contrast, similar SiO₂ capped devices, fabricated without the CdS passivating layer, show a large increase in leakage current when subjected to the same thermal cycle. Leakage current versus mesa diameter measurements suggest these results are due to reduce surface recombination at the exposed mesa sidewall. X-ray photoelectron spectroscopy (XPS) results indicate the S:Cd ratio of these films to be 0.77.     

4H-SiC紫外光电探测器光电特性随温度变化的研究

利用光电流谱法研究了300K到60K温度范围内的p-i-n结构4H-SiC紫外光电探测器的暗电流及相对光谱响应特性。研究发现随着温度的降低,探测器的暗电流和相对光谱响应都逐渐减小;而且,反向偏压越高,暗电流减小的速率越大。在零偏压下,随着温度的降低,器件的温度从300K降低到60K时,相对光谱响应的峰值波长先向短波方向移动,后向长波方向移动,在60K时移至从272nm附近移至282nm附近;同时观察到探测器的相对光谱响应范围略有缩小,。此外,我们对器件并讨论了温度变化对器件p、i、n各层产生的光电流随温度变化的机理进行讨论,提出了可以通过减少i层缺陷和适当减小n层的掺杂浓度的方式来提高器件的相对光谱响应。     

p-i-n结构GaN光电探测器性能的研究

近年来,可见盲与太阳盲光电探测器在火灾监控、太空通信和导弹尾焰探测等方面的应用引起了越来越多的关注。由于氮化镓(GaN)是直接宽带隙半导体材料,所以成为了在可见区与紫外区的光电器件的首选材料,而p-i-n结构的器件因其响应度高、暗电流低、便于集成等优点倍受人们的青睐。采用金属有机气相外延(MOCVD)法制备了p-i-n结构的GaN紫外光电探测器。在此基础上,采用N2气氛下热退火处理的方法,提高了p型GaN层的载流子浓度,从而降低了器件的暗电流。器件在1 V偏压下,暗电流仅为65 pA。器件在1 V偏压下的最大响应度值出现在361 nm处,大小为0.92 A/W。     

Novel D-A-D type small-molecular hole transport materials for stable inverted perovskite solar cells

Hole transport materials (HTMs), as a critical role in the hole extraction and transportation processes, highly influence the efficiency and stability of perovskite solar cells (PSCs). Despite that several efficient dopant-free HTMs have been reported, there is still no clear structure-property relationship that could give instructions for the rational molecular design of efficient HTMs. Thus, in this work, a series of donor–acceptor-donor (D–A–D) type carbazole-based small molecules, TM-1 to TM-4, have been carefully designed and synthesized. By varing the electron acceptor unit from benzene to pyridine, pyrazine and diazine, their packing structure in single crystals, optical and electronic properties have shown a great difference. While as dopant-free HTM in p-i-n type PSCs, TM-2 improved the device photovoltaic performance with a power conversion efficiency from 15.02% (based on PEDOT:PSS) to 16.13%. Moreover, the unencapsulated device based on TM-2 retains about 80% of its initial efficiency after 500 h storage in ambient environment, showing the superior stability.     

背照式InGaN紫外探测器的制备与数值模拟

研究了背照式InGaN p-i-n结构的紫外探测器的制备与数值模拟.通过低压金属有机化学气相沉积(MOCVD)方法生长p-GaN/i-InGaN/n-GaN外延片,采用标准的Ⅲ-Ⅴ族器件制备工艺,成功制备出p-i-n结构的InGaN紫外探测器.探测器台面半径为30 μm,在-5V偏压下暗电流为-6.47×10 1 2 A,对应的电流密度为2.29×10-7 A/cm2.该探测器响应波段为360～380 nm,在371 nm处达到峰值响应率为0.21 A/W,对应的外量子效率为70％,内量子效率为78.4％.零偏压下,优值因子R0A=5.66×107 Ω·cm2,对应的探测率D* =2.34×1013 cm·Hz1/2·W-1.同时,利用Silvaco TCAD软件进行数值模拟,响应率曲线仿真值与实验值拟合较好.     

超宽带开关矩阵的研制

介绍了一种采用p-i-n开关设计的单路选通开关矩阵。通过合理设计p-i-n二极管的直流反偏电压,解决了p-i-n开关矩阵承受功率的设计问题;采用宽带锥形电感和空心电感相结合的电路形式,设计了一种宽带的偏置电路;优化了开关矩阵电路的设计,简化了电路结构形式,提高了开关矩阵的微波性能和可生产性。设计实现了一种超宽带单路选通开关矩阵,工作频率为1～18 GHz,插入损耗(IL)<5 dB,端口隔离(Isolation)>35 dB。验证结果表明,理论仿真结果与实验测试结果基本一致,证明了设计方法的可行性。     

CMOS兼容近红外Si0.7Ge0.3/Si p-i-n(SOI)光电探测器

报道了一种采用UHV/CVD锗硅工艺和CMOS工艺流程在SOI衬底上制作的横向叉指状Si0.7Ge0.3/Si p-i-n光电探测器.测试结果表明:其工作波长范围为0.7～1.1μm,在峰值响应波长为0.93μm,响应度为0.38A/W.在3.0V的偏压下,其暗电流小于1nA,寄生电容小于1.0pF,上升时间为2.5ns.其良好的光电特性以及与CMOS工艺的兼容性,为研制能有效工作于近红外光的高速、低工作电压硅基光电集成器件提供了一种新的尝试,在高速光信号探测等应用中有一定的价值.     

具有新型电子传输层的有机薄膜电致发光器件

将8-hydroxy-quinolinato lithium(Liq)掺入4'7-diphyenyl-1,10-phenanthroline(BPhen)作为n型电子传输层(ETL),将tetrafluro-tetracyano-quinodimethane(F4-TCNQ)掺入4,4',4"-tris(3-methylphenylphenylamono)triphenylamine(m-MTDATA)作为p型空穴传输层(HTL),制作了p-i-n结构有机电致发光器件.为了检验传输层传导率的改善情况,制备了一系列单一空穴器件和单一电子器件.在引入BPhen:33wt% Liq作为ETL后,x% F4-TCNQ:m-MTDATA作为HTL后,器件的电流和功率效率明显改善.与控制器件(未掺杂)相比,性能最佳的掺杂器件的电流及功率效率分别提高了51%和89%,电压下降了29%.这是由于传输层传导能力的提高使得载流子在发光区域达到有效平衡.     

Numerical simulation of the effect of the free carrier motilities on light-soaked a-Si:H p-i-n solar cellL. Ayat1, A.F. Bouhdjar2, AF. Meftah2*, N. Sengouga2, AM. Meftah2

Using a previous model, which was developed to describe the light-induced creation of the defect density in the a-Si:H gap states, we present in this work a computer simulation of the a-Si:H p-i-n solar cell behavior under continuous illumination. We have considered the simple case of a monochromatic light beam nonuniformly absorbed. As a consequence of this light-absorption profile, the increase of the dangling bond density is assumed to be inhomogeneous over the intrinsic layer (i-layer). We investigate the internal variable profiles during illumination to understand in more detail the changes resulting from the light-induced degradation effect. Changes in the cell external parameters including the open circuit voltage, V_oc, the short circuit current density, J_sc, the fill factor, FF, and the maximum power density, P_max, are also presented. This shows, in addition, the free carrier mobility influence. The obtained results show that V_oc seems to be the less affected parameter by the light-induced increase of the dangling bond density. Moreover, its degradation is very weak-sensitive to the free carrier mobility. Finally, the free hole mobility effect is found to be more important than that of electrons in the improvement of the solar cell performance.     

薄p型层GaN基p-i-n型紫外探测器的反向漏电特性

制备了薄p型层GaN基p-i-n型紫外探测器,并对其反向漏电特性进行了研究。探测器材料采用金属有机化学气相沉积(MOCVD)方法在蓝宝石衬底上外延生长获得,p-GaN的厚度为30nm。基于该材料制作了具有共面电极的探测器器件,并采用SiO2对刻蚀侧壁进行了钝化。测试结果表明,结面积为1.825×10-4cm2的器件在-1V时的反向漏电流面密度为3.0×10-9 A/cm2,优质因子达到3.7×109Ω.cm2。