A polarization mismatched p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure to improve the hole injection for GaN based micro-LED with secondary etched mesa

A low hole injection efficiency for InGaN/GaN micro-light-emitting diodes(μLEDs) has become one of the main bottlenecks affecting the improvement of the external quantum efficiency(EQE) and the optical power. In this work, we propose and fabricate a polarization mismatched p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure for 445 nm GaN-based μLEDs with the size of 40 × 40 μm^(2), which serves as the hole injection layer. The polarization-induced electric field in the p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure provides holes with more energy and can facilitate the non-equilibrium holes to transport into the active region for radiative recombination. Meanwhile, a secondary etched mesa for μLEDs is also designed, which can effectively keep the holes apart from the defected region of the mesa sidewalls, and the surface nonradiative recombination can be suppressed. Therefore, the proposed μLED with the secondary etched mesa and the p-GaN/p-Al_(0.25)Ga_(0.75)N/p-GaN structure has the enhanced EQE and the improved optical power density when compared with the μLED without such designs.

Simulation study of blue InGaN multiple quantum well light-emitting diodes with different hole injection layers

InGaN-based light-emitting diodes with p-GaN and p-A1GaN hole injection layers are numerically studied using the APSYS simulation software. The simulation results indicate that light-emitting diodes with p-A1GaN hole injection layers show superior optical and electrical performance, such as an increase in light output power, a reduction in current leakage and alleviation of efficiency droop. These improvements can be attributed to the p-A1GaN serving as hole injection layers, which can alleviate the band bending induced by the polarization field, thereby improving both the hole injection efficiency and the electron blocking efficiency.

SQL Injection和CSS Hole入侵解决方案研究

文章着重论述了“SQL In jection”和“CSS Ho le”攻击的原理,通过对目前最流行的Sq l注入技术和CSS漏洞入侵技术的常用攻击方法做了详细具体的分析,并针对每种攻击方法提出了相应的防御解决方案.

Comparison of hot-hole injections in ultrashort channel LDD nMOSFETs with ultrathin oxide under an alternating stress

The behaviours of three types of hot-hole injections in ultrashort channel lightly doped drain （LDD） nMOSFETs with ultrathin oxide under an alternating stress have been compared. The three types of hot-hole injections, i.e. low gate voltage hot hole injection （LGVHHI）, gate-induced drain leakage induced hot-hole injection （GIDLIHHI） and substrate hot-hole injection （SHHI）, have different influences on the devices damaged already by the previous hot electron injection （HEI） because of the different locations of trapping holes and interface states induced by the three types of injections, i.e. three types of stresses. Experimental results show that GIDLIHHI and LGVHHI cannot recover the degradation of electron trapping, but SHHI can. Although SHHI can recover the device＇s performance, the recovery is slight and reaches saturation quickly, which is suggested here to be attributed to the fact that trapped holes are too few and the equilibrium is reached between the trapping and releasing of holes which can be set up quickly in the ultrathin oxide.

The performance enhancement in organic light-emitting diode using a semicrystalline composite for hole injection

A semicrystalline composite, 3, 4, 9, 10 perylenetetracarboxylic dianhydride （PTCDA） doped N,N＇-di（1-naphthyl）- N,N＇-diphenylbenzidine （NPB）, has been fabricated and characterized. An organic light-emitting diode using such a composite in hole injection exhibits the improved performance as compared with the reference device using neat NPB in hole injection. For example, at a luminance of 2000 cd/m2, the former device gives a current efficiency of 2.0cd/A, higher than 1.6cd/A obtained from the latter device. Furthermore, the semicrystalline composite has been shown thermally to be more stable than the neat NPB thin film, which is useful for making organic light emitting diodes with a prolonged lifetime.

Enhanced Hole-Injection Property in an OLED with a Self-assembled Monolayer of Hole-Transporting TPD on Thin Au as the Anode

A thioester-functionalized triphenylamine hole-transporting molecule （TPD-SAc） was synthesized and self-assembled to form a monolayer on an ultra-thin Au film supported on indium-tin oxide glass. The modified surface was characterized by aqueous contact angle, ellipsometer, atomic force microscopy, X-ray photoelectron spectroscopy, and ultraviolet pho- toelectron spectrometer to substantiate the formation of compact and pinhole-free monolayers. The modified organic light emitting diode device [indium-tin oxide/Au （5 nm）/self-assembled monolayers （SAM）/TPD （50 nm）/Alq3 （40 nm）/TPBI （15 nm）/LiF （1 nm）/A1 （100 nm）] showed a luminance of 7303.90 cd/m^2 and a current efficiency of 8.49 cd/A with 1.78 and 2.29-fold increase, respectively, compared to the control device without SAM. The improvements were attributed to the enhanced compatibility of the organic-inorganic interface, matched energy level by introduction of an energy mediating step and superior hole-injection property of SAM molecules.

Macular hole closure following anti-vascular endothelial growth factor injection in an eye with myopic choroidal neovascularization

Dear Editor,I am Cheolmin Yun,from the Department of Ophthalmology,Korea University College of Medicine.I write to present a case report of a female patient with a myopic patient suffering from atrophic choroidal neovascularization（CNV）and a full thickness macular hole（FTMH）,who was treated with an intravitreal anti-vascular endothelial growth factor （VEGF） injection without vitrectomy.

Performance improvement of GaN-based light-emitting diode with a p-InAlGaN hole injection layer

The characteristics of a blue light-emitting diode （LED） with a p-InA1GaN hole injection layer （HIL） is analyzed numerically. The simulation results indicate that the newly designed structure presents superior optical and electrical performance such as an increase in light output power, a reduction in current leakage and alleviation of efficiency droop. These improvements can be attributed to the p-InA1GaN serving as hole injection layers, which can alleviate the band bending induced by the polarization field, thereby improving both the hole injection efficiency and the electron blocking efficiency.

Improvement of Performance of Organic Light-Emitting Diodes with Both a MoO3 Hole Injection Layer and a MoO3 Doped Hole Transport Layer

We improve the performance of organic light-emitting diodes （OLEDs） with both a MoO3 hole injection layer （HIL） and a MoO3 doped hole transport layer （HTL）, and present a systematical and comparative investigation on these devices. Compared with OLEDs with only MoO3 HIL or MoO3 doped HTL, OLEDs with both MoO3 HIL and MoO3 doped HTL show superior performance in driving voltage, power efficiency, and stability. Based on the typical NPB/Alq3 heterojunction structure, OLEDs with both MoO3 HIL and MoO3 doped HTL show a driving voltage of 5.4 V and a power efficiency of 1.41 lm/W for 1000 cd/m2, and a lifetime of around 0. 88 h with an initial luminance of 5268 cd/m2 under a constant current of 190 mA/cm2 operation in air without encapsulation. While OLEDs with only MoO3 HIL or MoO3 doped HTL show higher driving voltages of 6.4 V or 5.8 V and lower power efficiencies of 1.201m/W or 1.341m/W for 1000cd/m2, and a shorter lifetime of 0.33 or 0.60h with an initial luminance of around 5122 or 5300cd/m2 under a constant current of 200 or 216mA/cm2 operation. Our results demonstrate clearly that using both MoO3 HIL and MoO3 doped HTL is a simple and effective approach to simultaneoasly improve both the hole injection and transport efficiency, resulting from the lowered energy barrier at the anode interface and the increased hole carrier density in MoO3 doped HTL.

Lowering the driving voltage and improving the luminance of blue fluorescent organic light-emitting devices by thermal annealing a hole injection layer of pentacene

We chose pentacene as a hole injection layer（HIL） to fabricate the high performance blue fluorescent organic lightemitting devices（OLEDs）. We found that the carrier mobility of the pentacene thin films could be efficiently improved after a critical annealing at temperature 120℃. Then we performed the tests of scanning electron microscopy, atomic force microscopy, and Kelvin probe to explore the effect of annealing on the pentacene films. The pentacene film exhibited a more crystalline form with better continuities and smoothness after annealing. The optimal device with 120℃ annealed pentacene film and n-doped electron transport layer（ETL） presents a low turn-on voltage of 2.6 V and a highest luminance of 134800 cd/m^2 at 12 V, which are reduced by 26% and improved by 50% compared with those of the control device.

Trench gate GaN IGBT with controlled hole injection efficiency

In this paper,a novel trench gate gallium nitride(GaN)insulated gate bipolar transistor(GaN IGBT),in which the collector is divided into multiple regions to control the hole injection efficiency,is designed and theoretically studied.The incorporation of a P+/P-multi-region alternating structure in the collector region mitigates hole injection within the collector region.When the device is in forward conduction,the conductivity modulation effect results in a reduced storage of carriers in the drift region.As a result,the number of carriers requiring extraction during device turn-off is minimized,leading to a faster turn-off speed.The results illustrate that the GaN IGBT with controlled hole injection efficiency(CEH GaN IGBT)exhibits markedly enhanced performance compared to conventional GaN IGBT,showing a remarkable 42.2%reduction in turn-off time and a notable 28.5%decrease in turn-off loss.

Efficiency droop suppression in GaN-based light-emitting diodes by chirped multiple quantum well structure at high current injection

Gallium nitride （GaN） based light-emitting diodes （LEDs） with chirped multiple quantum well （MQW） structures have been investigated experimentally and numerically in this paper. Compared to conventional LEDs with uniform quantum wells （QWs）, LEDs with chirped MQW structures have better internal quantum efficiency （IQE） and carrier injection efficiency. The droop ratios of LEDs with chirped MQW structures show a remarkable improvement at 600 mA/mm2, reduced down from 28.6% （conventional uniform LEDs） to 23.7% （chirped MQWs-a） and 18.6% （chirped MQWs-b）, respectively. Meanwhile, the peak IQE increases from 76.9% （uniform LEDs） to 83.7% （chirped MQWs-a） and 88.6% （chirped MQWs-b）. The reservoir effect of chirped MQW structures is the significant reason as it could increase hole injection efficiency and radiative recombination. The leakage current and Auger recombination of chirped MQW structures can also be suppressed. Furthermore, the chirped MQWs-b structure with lower potential barriers can enhance the reservoir effect and obtain further improvement of the carrier injection efficiency and radiative recombination, as well as further suppressing efficiency droop.

Study on Dust-Control WaterInjection in Fully-Mchanized Top-Coal Caving Longwall Faces

Based on the analysis of the top-coal movement, the appropriate position of holes through which dustcoutrol water is injected is confirmed. And a practical test has been carried out, which has achieved good reuslts both in dust control and in the flow rate of water injected into coal.

应用油水井联动测试优化不稳定注水参数方法研究

随着油田开发时间的延长,常规注水波及范围相对固定,技术适应性逐渐变差,采用以注水量增减或注水井停开的周期注水是一种有效的提高采收率的方法。本文提出通过对多个周期注水的井组开展油水井联动测试,即在注水量周期性变化或停注开注过程中,监测注入井和采出井井底流压变化,以此来对不稳定注水的波动幅度和波动周期进行优化。该方法操作简单,受外界因素影响小,适用于不同不稳定注水油藏参数优化。

某摩托车发动机进气歧管二次抽芯注塑模具设计

川崎摩托车发动机进气歧管结构复杂。产品侧孔内有斜孔,侧孔抽芯脱模力大,为此设计了2处二次抽芯机构。在动、定模两侧设计了斜顶抽芯机构,为了实现定模侧的斜向抽芯,模具在三板模的基础上增加了一块板,因此模具有4个分型面,为此设计了顺序定距分型机构。结果表明,所设计的模具结构合理,动作可靠,可以满足生产要求。

LiCl掺杂PEDOT∶PSS提高蓝光量子点发光二极管的性能

基于全溶液制备的量子点发光二极管(QLEDs)通常存在电子-空穴注入不平衡的问题,严重地限制了蓝光QLEDs器件性能的提升。本文研究了不同浓度的金属卤化物(Li Cl)掺杂对聚(乙烯二氧噻吩)∶聚苯乙烯磺酸盐(PEDOT∶PSS)薄膜的形貌、导电率、透光性以及所制备QLEDs器件性能的影响规律。实验结果表明,Li Cl的掺杂浓度(质量分数)为2%时蓝光QLED器件性能的提升效果最佳,这主要归因于Li Cl掺杂后的PEDOT∶PSS薄膜导电率和透光性的增强以及器件中空穴注入效率的提高。相较于未掺杂的PEDOT∶PSS基QLED器件,基于Li Cl掺杂的蓝光QLED器件的最大亮度、峰值电流效率、峰值功率效率和峰值外量子效率分别从5 083 cd·m^(-2)、0.91 cd·A^(-1)、0.59 lm·W^(-1)和2.31%提升到7 451 cd·m^(-2)、1.38 cd·A^(-1)、0.89 lm·W^(-1)和3.51%。结果表明,采用Li Cl掺杂PEDOT∶PSS空穴注入层是提高蓝光QLED性能的一种有效策略。

卧式三角型滤筒的脉冲喷吹清灰性能

【目的】为优化卧式三角型滤筒除尘器的清灰性能,探究不同喷吹气流对滤筒内部压力分布的影响,获得不同喷吹孔型式对三角型滤筒的清灰性能的影响规律。【方法】分别采用直管喷吹孔、文氏里管、散射喷嘴、新型曲面诱导引射器共4种喷吹孔型式的诱导引流装置对卧式三角型滤筒开展冷态脉冲实验,以侧壁压强峰值和相对标准偏差作为评价清灰性能的技术指标,分别探讨不同条件下的喷吹射流对滤筒内壁压力分布的影响。【结果】在喷吹压强分别设为0.3、0.4、0.5 MPa的条件下,采用直管、文丘里管、新型曲面诱导引射器时喷吹距离分别设为150、200、250、300、350、400 mm,采用散射喷嘴时喷吹距离分别设为25、50、75、100、125、150、175 mm,则采用直管、文丘里管、散射喷嘴、新型曲面诱导引射器时的平均侧壁压强峰值分别为1037、1758、952、1533 Pa,相对标准偏差分别为0.76、0.58、0.09、0.16;采用新型曲面诱导引射器喷吹孔时,比采用散射喷嘴时的清灰强度高61%,比采用文丘里管时的相对标准偏差小0.47。【结论】新型曲面诱导引射器同时兼顾对侧壁压强峰值和相对标准偏差的要求,在4种喷吹孔型式中清灰性能最佳。

土壤秸秆注孔对土壤含水量及作物生长的影响

[目的]研究土壤秸秆注孔对土壤含水量及作物生长的影响,为旱作农田增加雨水蓄集能力及提高水分利用效率提供理论依据。[方法]开展玉米—小麦轮作田间试验,设置常规种植(CK)、土壤秸秆注孔2孔/m^(2)(T_(1)),4孔/m^(2)(T_(2)),8孔/m^(2)(T_(3))4个处理。[结果]秸秆注孔所有处理均提高了整个试验期表层土壤含水量。T_(2),T_(3)处理提高了收获期深层土壤含水量,试验结束时两者底层土壤(60—80cm)含水量较CK分别提高了29.19%和28.18%。秸秆注孔处理提高了作物株高、经济产量和生物量,以及降水利用效率和水分利用效率,T_(2),T_(3)处理的提高效果最明显,且彼此差异不显著。[结论]秸秆注孔具有保水性能和增产能力,根据成本和效果综合考虑,推荐秸秆注孔4孔/m^(2)(T_(2))作为优选处理。

深部煤系储层缝间干扰多裂缝同步扩展规律试验研究

为研究深部煤系储层缝间干扰多裂缝同步扩展规律,采用自行研制的TCHFSM-I型大尺寸真三轴压裂渗流模拟装置,开展不同压裂孔间距、不同注液速率对多裂缝同步扩展规律的影响试验。通过观察和分析压裂过程中裂缝扩展形态、注液压力演化规律,以及声发射动态响应特征和注液流量演化特征,结果表明:压裂孔间距较小时,左右两侧裂缝扩展长度大于中部裂缝,随着压裂孔间距增大,左中右3条裂缝均衡扩展;增大注液速率可以使起裂压力增高,多裂缝长度增加,有效提高储层改造体积;增大压裂孔间距和注液速率,可以使左中右3个压裂孔的注液流量占比更均衡。

微纳级GaN基VCSEL中周期反射结构与电子阻挡层的设置作用分析

氮化镓(GaN)基微纳米结构生长技术的成熟为微纳级GaN基垂直腔面发射激光器(VCSEL)的制备提供了新的途径。本文设计了基于GaN基轴向异质结微纳米柱的微纳级VCSEL结构,采用Al_(0.8)Ga_(0.2)N/In_(0.2)Ga_(0.8)N应变补偿结构作为上下分布式布拉格反射镜(DBR),其中Al_(0.8)Ga_(0.2)N层的Al组分远高于传统结构中的电子阻挡层(EBL),能够更好地起到电子阻挡的作用。本文使用商用软件PICS3D构建了电子阻挡层处于不同位置的VCSEL数理模型,并进行数值模拟计算,探索和分析物理机理,解释了不同位置EBL对空穴注入效率的影响。结果表明,采用Al_(0.8)Ga_(0.2)N与In_(0.2)Ga_(0.8)N组成的应变补偿DBR可以更好地提高空穴注入效率,优化器件光电性能。