Optoelectronic properties analysis of silicon light-emitting diode monolithically integrated in standard CMOS IC

Si p^+n junction diodes operating in the mode of avalanche breakdown are capable of emitting light in the visible range of 400-900 nm. In this study, to realize the switching speed in the GHz range, we present a transient model to shorten the carrier lifetime in the high electric field region by accumulating carriers in both p and n type regions. We also verify the optoelectronic characteristics by disclosing the related physical mechanisms behind the light emission phenomena. The emission of visible light by a monolithically integrated Si diode under the reverse bias is also discussed. The light is emitted as spatial sources by the defects located at the p-n junction of the reverse-biased diode. The influence of the defects on the electrical behavior is manifested as a current-dependent electroluminescence.

Highly efficient silicon light emitting diodes produced by doping engineering

This paper reviews our recent progress on silicon （Si） pn junction light emitting diodes with locally doping engineered carrier potentials. Boron implanted Si diodes with dislocation loops have electroluminescence （EL） quantum efficiency up to 0.12%, which is two orders of magnitude higher than those without dislocations. Boron gettering along the strained dislocation lines produces locally p-type spike doping at the dislocations, which have potential wells for bounding spatially indirect excitons. Thermal dissociation of the bound excitons releases free carriers, leading to an anomalous increase of the band to band luminescence with increasing tempera- ture. Si light emitting diodes with external quantum efficiency of 0.2% have been also demonstrated by implementation of pnpn modulation doping arrays.

Multifunctional silicon-based light emitting device in standard complementary metal oxide semiconductor technology

A three-terminal silicon-based light emitting device is proposed and fabricated in standard 0.35 μm complementary metal-oxide-semiconductor technology. This device is capable of versatile working modes： it can emit visible to near infra-red （NIR） light （the spectrum ranges from 500 nm to 1000 nm） in reverse bias avalanche breakdown mode with working voltage between 8.35 V-12 V and emit NIR light （the spectrum ranges from 900 nm to 1300 nm） in the forward injection mode with working voltage below 2 V. An apparent modulation effect on the light intensity from the polysilicon gate is observed in the forward injection mode. Furthermore, when the gate oxide is broken down, NIR light is emitted from the polysilicon/oxide/silicon structure. Optoelectronic characteristics of the device working in different modes are measured and compared. The mechanisms behind these different emissions are explored.

Vitrectomy combined with silicone oil tamponade in the treatment of severely traumatized eyes with the visual acuity of no light perception

AIM: To evaluate the efficacy of surgical treatment of vitrectomy combined with silicone oil tamponade in the treatment of severely traumatized eyes with the visual acuity of no light perception (NLP).METHODS: This was a retrospective uncontrolled interventional case-series of 19 patients of severely traumatized eyes with NLP who underwent vitrectomy surgery at the Affiliated Hospital of Medical College, Qingdao University (Qingdao, China) during a 3-year period. We recorded perioperative factors with the potential to influence functional outcome including duration from the injury to intervention; causes for ocular trauma; open globe or closed globe injury; grade of vitreous hemorrhage; grade of endophthalmitis; grade of retinal detachment; size and location of intraocular foreign body (IOFB); extent and position of retinal defect; grade of proliferative vitreoretinopathy (PVR); type of surgery; perioperative complications and tamponade agent. The follow-up time was from 3 to 18 months, and the mean time was 12 months.RESULTS: After a mean follow-up period of 12 months (3-18 months) 10.53% (2/19) of eyes had visual acuity of between 20/60 and 20/400, 52.63% (10/19) had visual acuity less than 20/400 but more than NLP, and 36.84% (7/19) remained NLP. Visual acuity was improved from NLP to light perception (LP) or better in 63.16% (12/19) of eyes and the rate of complete retinal reattachment was 73.68% (14/19). Good visual acuity all resulted from those patients of blunt trauma with intact eyewall (closed globe injury). The perioperative factors of poor visual acuity prognosis included delayed intervention; open globe injury; endophthalmitis; severe retinal detachment; large IOFB; macular defect; a wide range of retinal defects andsevere PVR.CONCLUSION: The main reasons of NLP after ocular trauma are severe vitreous hemorrhage opacity; refractive media opacity; retinal detachment; retinal and uveal damages and defects, especially defects of the macula; PVR and endophthalmitis. NLP after ocular trauma in some cases does not mean permanent vision loss. Early intervention of vitrectomy combined with silicone oil tamponade and achieving retinal reattachment of the remaining retina, may make the severely traumatized eyes regain the VA of LP or better.

Effects of light-mass structural forms on silicon carbide mirror

To reduce the mass of the mirror,silicon carbide was used as the material and four light-mass structures were designed. The properties of SiC mirror open back structure with triangular cell,open back structure with hexagonal cell,sandwich structure with triangular cell,sandwich structure with hexagonal cell,were analyzed by using finite element method. The results of the static,dynamic,and thermal properties of the four kinds of SiC mirror indicate that the surface figures of the SiC mirrors are all satisfactory with the design requirements. The properties of the mirrors with sandwich structure are better than those with open back structure,except the high cost. And the mirror with triangular cell has better combination properties than the mirror with hexagonal cell. Considering the overall performance and the cost,open back structure with triangular cell is the most suitable for the SiC mirror.

Ohmic Hetero-Junction of n-Type Silicon and Tungsten Trioxide for Visible-Light Sensitive Photocatalyst

Visible light-sensitive photocatalyst was developed by combining n-type silicon (n-Si) and tungsten trioxide (WO3, n-Si/WO3), yielding an ohmic contact in between. In this system, the ohmic contact acted as an electron-and-hole mediator for the transfer of electrons and holes in the conduction band (CB) of WO3 and in the valence band (VB) of n-Si, respectively. Utilizing thus- constructed n-Si/WO3, the decomposition of 2-propanolto CO2 via acetone was achieved under visible light irradiation, by the contribution of holes in the VB of WO3 to decompose 2-propanol and the consumption of electrons in the CB of n-Si to reduce O2. The combination of p-type Si (p-Si) and WO3 (p-Si/ WO3), not the ohmic contact but the rectifying contact, was much less effective, compared to n-Si/WO3.

Low insertion loss silicon-based spatial light modulator with high reflective materials outside Fabry–Perot cavity

The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth: their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.

用于单片集成传感系统的多晶硅级联自发光器件研究

针对全硅光电生物传感器的硅基单片集成应用需求,提出了基于多晶硅级联自发光器件的单片集成传感器,对其中作为关键部分的多晶硅光源进行了试制,采用标准0.35μm的CMOS工艺对该光源进行了流片验证,并设计了适配的全硅波导检测结构。结果表明,多晶硅光源发光特征峰为635 nm、700 nm和785 nm,该特征峰作为波导入射光源时,设计的全硅波导检测结构能够实现检测目的。

光固化3D打印技术制备氮化硅陶瓷研究进展

氮化硅陶瓷(Si_(3)N4)具有硬度高、耐磨性好、生物相容性好等优点,因此通过增材制造手段制备复杂形状的Si_(3)N4陶瓷是近几年的研究热点,通过数字光处理成型技术(DLP)可以快速制备传统手段难以制备的复杂形状陶瓷,成型精度高、成型效率快且极具个性化。分别从Si_(3)N4陶瓷浆料的制备、光固化特性以及素坯的烧结工艺等方面进行分析,详细阐述了DLP光固化制备Si_(3)N4陶瓷的研究现状,并对其发展趋势进行展望。

光固化3D打印SiC:粉体氧化处理提升浆料UV固化性能

为了进行碳化硅(SiC)的光固化3D打印,本文提出采用表面氧化处理提升SiC浆料的光固化性能。采用扫描电子显微镜、X射线衍射仪、X射线光电子能谱等研究了SiC颗粒的氧化过程以及氧化温度与保温时间对氧化过程的影响;采用动态流变仪、紫外分光光度计、数字千分尺等研究了浆料的流变性能和光固化性能。结果表明:经表面氧化处理后的SiC颗粒紫外反射率有显著的提高,最高为48.11%,为未氧化SiC颗粒的1.8倍;配制的浆料光固化性能有明显的改善,曝光5 s时固化厚度最高为76μm,为未氧化的3.6倍。随着氧化温度的上升以及保温时间的延长,氧化层厚度持续增长,最高达到144.8 nm。考虑到过度氧化不利于后续SiC陶瓷的烧结成型,最终选择使用1100℃保温3.0 h的氧化SiC粉末,并以1%(质量分数)的KOS163为SiC浆料的分散剂,制备了固含量为45%(体积分数)的SiC浆料,成功实现了SiC陶瓷坯体的光固化3D打印。

全数字PET关键器件硅光电倍增器研究进展

近年来,硅光电倍增器(SiPM)凭借其出色的性能表现,已经成为正电子发射断层成像(PET)中的首选光电转换器件。SiPM具有单光子分辨能力和低于100 ps的时间分辨率,使得精确测量光子到达时间成为可能,催生了飞行时间PET、光子计数计算机断层扫描、正电子素寿命显像等新兴应用领域,这些应用又对SiPM的性能提出了更高的挑战。因此,如何将SiPM性能推进至其物理极限已成为新一代SiPM的研究的关键方向。在传统的SiPM架构中,信号经过多次处理和模数转换,带来噪声增加和时间性能恶化的问题,从而限制了SiPM的性能潜力。随着半导体制造工艺的快速发展,SiPM可在标准CMOS工艺节点上制造,标志着可以将数字逻辑集成在SiPM器件内,这是SiPM领域的一次重大突破,使我们能在单一SiPM内实现更精确的时间、能量、位置信息获取,为推进SiPM达到性能极限提供了一条可能的途径。本文综述SiPM的发展历史、工作原理和性能参数,分析传统SiPM的局限性,梳理数字SiPM研究的关键问题,介绍当前几种数字化SiPM架构,最后对数字SiPM的关键技术进行总结和展望。

光注入提升晶体硅异质结太阳电池性能的研究

该文制备工业尺寸的晶体硅异质结太阳电池,研究光注入对电池光电性能的影响。实验结果表明:光注入有效提升了晶体硅异质结太阳电池的光电转换效率,经过光注入后电池光电转换绝对效率提升了0.33%,均值达到24.47个百分点。对比光注入前后的光电性能参数,其效率提升的主要因素是光注入使得电池的填充因子被有效提升。结合光注入前后电池的Suns-Voc测试,证实了光注入能使电池的串联电阻大比例降低。因此,光注入改善电池性能的主要物理原因可归结为:串联电阻的降低提升了电池的填充因子。

用于紫外光辅助直书写3D打印的光敏硅橡胶墨水性能研究

基于巯烯点击化学反应,制备了一系列可用于紫外光辅助直书写3D打印的硅橡胶墨水,利用旋转流变仪、固体流变仪、紫外可见分光光度计等分析了交联剂巯基含量、白炭黑用量对光敏硅橡胶墨水流变性、透光性、光固化深度和力学性能的影响。结果表明,白炭黑用量和交联剂巯基含量的增加均能提高墨水的屈服应力,同时降低制品的透明性,从而降低固化深度;制品的力学性能受交联剂巯基含量、白炭黑补强效应、固化深度的综合影响。当交联剂巯基含量较低时,制品拉伸强度随白炭黑用量的增加而提高;但当交联剂巯基含量很高时,较高的白炭黑用量反而会降低制品的力学强度;可根据需求调节交联剂巯基含量和白炭黑用量,进而平衡墨水的各项性能,使墨水具有良好的可打印性。采用紫外光辅助直书写3D打印,可实现一般直写技术难以完成的无塌陷、大跨距结构的制备。

锌掺杂荧光硅量子点作为叶面光肥对生菜生长的影响

以N-氨乙基-γ-氨丙基二甲氧基硅烷分子(DAMO)作为硅源,采用水热法合成一种高分散性、光学性能稳定的锌掺杂荧光硅量子点(Si@Zn QDs)。以Si@Zn QDs作为叶面光肥,吸收太阳光中不被植物利用的紫外光,发出能使生菜吸收进行光合作用的蓝光,提高了光能利用率。通过14 d的水培试验评估Si@Zn QDs作为叶面光肥对生菜生长的影响。结果表明,Si@Zn QDs与生菜的叶绿体(CLP)复合后,提高了希尔反应活性,当锌掺杂量达0.1%时,对生菜生长的促进效果最明显。与对照组相比,干质量和鲜质量分别增加41.64%和52.20%。Si@Zn 0.1%QDs(100 mg·L^(-1))使生菜叶片中叶绿素a、叶绿素b、总叶绿素、类胡萝卜素和蛋白质含量分别提高60.56%、56.37%、61.20%、49.75%和29.90%。这项工作为锌掺杂荧光硅量子点在植物光合作用中的应用提供了科学依据。

基于超像素的硅基有机发光二极管微显示器

基于超像素技术,针对彩色硅基OLED(Organic Light Emitting Diode)微显示器,提出一种数字驱动策略,通过复用相邻像素信息,使单像素用于多个相邻像素成像,大幅提高显示分辨率.设计了一种数字驱动彩色OLEDoS(Organic Light Emitting Diode on Silicon)微显示器驱动电路,在120 Hz帧频的条件下,可实现256级灰度和4K显示分辨率,且电路面积和每秒数据传输量仅为传统驱动方式的50%.经测试验证,该驱动电路可实现的OLED像素平均电流范围为13.1 pA~3.74 nA,可满足微显示器近眼显示需求.

汽车顶灯集成拨扭按键设计与分析

随着乘用车市场竞争越来越激烈,用户对汽车内饰操作体验的要求也越来越高。在汽车发展的过程中,前排顶灯功能的集成度也在不断增强,通常需要集成天窗、遮阳帘、滑移门等操作开关按键。文章重点讨论前排顶灯中开关按键在按键结构设计过程中的相关指标参数,并分析硅橡胶对开关操作手感的影响,期望能为开发人员提供一些参考,从而提高汽车产品的市场竞争力。

Shortening turn-on delay of SiC light triggered thyristor by7-shaped thin n-base doping profile

A new 4 H–SiC light triggered thyristor（LTT） with 7-shaped thin n-base doping profile is proposed and simulated using a two-dimensional numerical method. In this new structure, the bottom region of the thin n-base has a graded doping profile to induce an accelerating electric field and compensate for the shortcoming of the double-layer thin n-base structure in transmitting injected holes. In addition, the accelerating electric field can also speed up the transmission of photongenerated carriers during light triggering. As a result, the current gain of the top pnp transistor of the SiC LTT is further increased. According to the TCAD simulations, the turn-on delay time of the SiC LTT decreases by about 91.5% compared with that of previous double-layer thin n-base SiC LTT. The minimum turn-on delay time of the SiC LTT is only 828 ns,when triggered by 100 mW/cm^2 ultraviolet light. Meanwhile, there is only a slight degradation in the forward blocking characteristic.

Injection modulation of p^+-n emitter junction in 4H-SiC light triggered thyristor by double-deck thin n-base

To overcome hole-injection limitation of p^＋-n emitter junction in 4H-SiC light triggered thyristor, a novel high- voltage 4H-SiC light triggered thyristor with double-deck thin n-base structure is proposed and demonstrated by two- dimensional numerical simulations. In this new structure, the conventional thin n-base is split to double-deck. The hole- injection of p^＋-n emitter junction is modulated by modulating the doping concentration and thickness of upper-deck thin n- base. With double-deck thin n-base, the current gain coefficient of the top pnp transistor in 4H-SiC light triggered thyristor is enhanced. As a result, the triggering light intensity and the turn-on delay time of 4H-SiC light triggered thyristor are both reduced. The simulation results show that the proposed 10-kV 4H-SiC light triggered thyristor is able to be triggered on by 500-mW/cm^2 ultraviolet light pulse. Meanwhile, the turn-on delay time of the proposed thyristor is reduced to 337 ns.

640×480像素矩阵OLED-on-silicon微显示芯片设计

描述了一种内置SRAM的640×480像素矩阵OLED-on-silicon单色微显示电路的设计。像素电流12nA～1.6μA可调。每个像素点面积不超过400μm2,信号最大扫描频率30MHz。采用charteredCMOS0.35μm18V高压工艺仿真设计,成功实现了OLED技术和CMOS工艺的结合。

外源硅滴施对弱光胁迫下冬小麦生长及生理特性的影响

【目的】研究外源硅滴施对弱光胁迫下冬小麦生长及生理特性的影响。【方法】于2018~2019年在新疆南疆采用盆栽试验进行,以新冬60号为材料,自冬小麦拔节期至成熟期,用黑色遮阳网进行25%遮阴处理,在冬小麦拔节期设置5个外源硅(Na_(2) SiO_(3)分析纯)滴施量分别为7.5 kg/hm^(2)(Si_(1))、15 kg/hm^(2)(Si_(2))、22.5 kg/hm^(2)(Si_(3))、30 kg/hm^(2)(Si_(4))、37.5 kg/hm^(2)(Si_(5))和清水对照(Si 0)共6个处理,测定不同处理冬小麦植株性状、叶片光合特性及小穗发育和籽粒性状,分析外源硅滴施对弱光胁迫下冬小麦调控效应,并筛选出适宜的外源硅滴施量。【结果】弱光胁迫下,外源硅滴施可以增加冬小麦的株高、茎粗、穗长和叶片SPAD值;改善了叶片光合性能,提高了旗叶的净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs);增加了可孕小穗数,降低了不孕小穗数;单茎生物量、穗粒数和穗粒重均明显提高;各指标在Si_(3)处理达到最优。【结论】硅能改善弱光胁迫下冬小麦植株的生长状况,提高光合作用,提高可孕小穗数、穗粒数和穗粒重,以外源硅滴施22.5 kg/hm^(2)时最佳。