Effects of gate dielectric thickness and semiconductor thickness on device performance of organic field-effect transistors based on pentacene

In this paper,the pentacene-based organic field-effect transistors(OFETs)with poly(methyl methacrylate)(PMMA)as gate dielectrics were fabricated,and the effects of gate dielectric thickness and semiconductor thickness on the device performance were investigated.The optimal PMMA thickness is in the range of 350–400 nm to sustain a considerable current density and stable performance.The device performance depends on the thicknesses of the active layer non-monotonically,which can be explained by the morphology of the pentacene film and the position of the conducting channel in the active layer.The device with a pentacene thickness of 50 nm shows the best performance,which has a maximum hole mobility of 1.12 cm2/V·s.In addition,the introduction of a thin layer of tris-(8-hydroxyquinolinato)aluminum(Alq3)to the OFETs as a light-emitting material greatly decreases the device performance.     

A betavoltaic microbattery based on PIN diodes

A betavoltaic Microbattery was studied.The diode was composed of a PIN structure with an active area of 10 mm×10 mm to collect the charge from a 10mCi Ni-63 source.An open circuit voltage of 0.16 V and a short circuit current density of 67.6 nA/cm2 were measured.An efficiency (η) of 1.44% was obtained.The performance of device was limited by high series resistance,edge recombination and attenuation of electron in PIN diodes.It is expected to be improved by optimizing the design and using more suitable radioisotope.     

Laminated all-solid state NiO/WO_3 complementary electrochromic device

Based on the previous studies on the rf reactive sputtered nickel oxide film with nanostructure and its electrochromism, i. e. electrochromic effect of the films is attributed to the reversible change of the non-stoichiometry in the nanocrystaltine gram boundaries and interfaces due to the injection and ejection of Li ions, a prototype of all-solid-state NiO/WO3 complementary electrochromic device using LixTaOy thin film as inorganic electrolyte was designed and prepared. The results indicate that the solar reflectance of the device could be modulated from 0. 15 in colored state to 0.60 in bleached state with excellent cyclic reversibility, durability and high response speed (less than 0.3 s from colored state to bleached state).     

Research on Integrated Monitoring and Prevention System for Stray Current in Metro

On the basis of analyzing the influencing factors and harmfulness of stray current, and discussing the existing problems of monitoring and prevention system for stray current, the integrated monitoring and prevention system for stray current in metro was developed. A net system of distributed computers for monitoring was set up, It can monitor the distribution of stray current in metro and the corrosion of the metal structure in the whole line. According to the situation of monitoring it can also control the drainage of its tank to reach the best effect and eliminate the negative effect of polarity drainage. By using the new type unilateral electric device, the problem of burning the rail by electric are ean be avoided. The uni!ateral electric device can be connected with the monitoring net system directly to realize the monitor in line and improve the reliability of the device.     

Surface modification of indium tin oxide by oxygen plasma immersion ion implantation

Organic electroluminescent device,also known as organic light-emitting diode (OLED),is a kind of solid state light emitting device by carrier injection which can directly transform electrical energy into luminous energy.Due to its low operating voltage,low energy consumption,high brightness,flexibility in the choice of materials and easy realization of full color display,OLED is the potential material both in the display and illumination fields.However,there is much scope to improve the efficiency,lifetime,and reduce the cost in mass production before OLEDs can replace traditional technology in some application fields.In this work,we report the oxygen plasma immersion ion implantation (PIII) to improve the surface oxygen ratio of ITO films for further increase of surface work function above the common treatment of O2 inductively coupled plasma (ICP).The ratio of oxygen content at the surface layer was improved to be much higher than by O2 ICP treatment.A further surface work function relative increase of 0.4e V above OICP sample and 0.4 eV above the as-prepared sample can be estimated by the peak relative shift in the X-ray photoelectron spectroscopy (XPS) diagram.Moreover,the XPS characterization was carried out at least 50 h after the PIII implantation to indicate that the surface modifying effects are stable.The variations of transparency and conductivity of the PIII treated ITO samples can be neglected.     

Synthesis of nanosized tungsten powder

Nanosized tungsten powder was synthesized by means of different methods and under different conditions with nanosized WO3 powder. The powder and the intermediate products were characterized using XRD, SEM, TEM, BET （Brunauer Emmett Teller Procedure） and SAXS （X-ray diffracto-spectrometer/Kratky small angle scattering goniometer）. The results show that nanosized WO3 can be completely reduced to WO2 at 600℃ after 40 min, and WO2 can be reduced to W at 700℃ after 90 min, moreover, the mean size of W particles is less than 40 nm. Furthermore, the process of WO3→WO2→W excelled that of WO3→W in getting stable nanosized tungsten powder with less grain size.     

Analytical Modeling of Dual Material Gate SOI MOSFET with Asymmetric Halo

A dual material gate silicon-on-insulator MOSFET with asymmetrical halo is presented to improve short channel effect and carder transport efficiency for the first time. The front gate consists of two metal gates with different work functions by making them contacting laterally, and the channel is more heavily doped near the source than in the rest. Using a three-region polynomial potential distribution and a universal boundary condition, a two-dimensional analytical model for the fully depleted silicon-on-insulator MOSFET is developed based on the explicit solution of two-dimensional Poisson＇s equation. The model includes the calculation of potential distribution along the channel and subthreshold current. The performance improvement of the novel silicon-on-insulator MOSFET is examined and compared with the traditional silicon-on-insulator MOSFET using the analytical model and two-dimensional device simulator MEDICI. It is found that the novel silicon-on-insulator MOSFET could not only suppress short channel effect, but also increase cartier transoort efficiency noticeably. The derived analytical model agrees well with MEDICI.     

Ultrahigh-performance planar β-Ga_2O_3 solar-blind Schottky photodiode detectors

The low dark current, high responsivity and high specific detectivity could be preferably achieved in detectors based on junctions, owing to the efficient constraint of carriers. Compared with the other junctions, planar Schottky junctions have simple structures and technological demands and are easy integrated. Herein, in this work, we prepared the β-Ga_2O_3 thin film by metalorganic chemical vapor deposition method to construct planar Ti/β-Ga_2O_3/Ni Schottky photodiode detectors with different onstate resistances. Fortunately, all the devices exhibit state-of-the-art performances, such as responsivity of 175–1372 A W~(-1),specific detectivity of 10~(14) Jones and external quantum efficiency of 85700%–671500%. In addition, the dependences of device performances on the on-state resistances indicate that the higher dark currents, photocurrents and photoresponsivities may well be obtained when on-state resistance is smaller, due to the less external power is used to overcome the impendence and condensance at the Ti/β-Ga_2O_3 and Ni/β-Ga_2O_3 interfaces, but contributing to higher electric current flow both in the dark and under illuminations.     

Vanadium Nitride Nanoparticles as Anode Material for Lithium Ion Hybrid Capacitor Applications

A high production efficiency synthesis method was used to produce a stacked vanadium nitride nanoparticle structure with an inexpensive raw material as an anode material and high surface area polystyrene was used the cathode material for lithium ion hybrid capacitors. The Li-HCs cell displayed an excellent specific capacitance of 64.2 F·g~(~(-1)) at a current density of 0.25 A·g~(-1) and a wide potential window of 0.01 to 3.5 V. Furthermore, the device exhibited a high energy density of 109.3 W·h·kg~(-1) at a power density of 512.3 W·kg~(-1) and retained an energy density of 69.2 W·h·kg~(-1) at a high power density of 3 498.9 W· kg~(-1) at 2 A·g~(-1). Due to the short synthesis time and simple raw materials, this method is suitable for industrial production.     

Novel LDNMOS embedded SCR with strong ESD robustness based on 0.5μm 18 V CDMOS technology

A novel LDNMOS embedded silicon controlled rectifier(SCR) was proposed to enhance ESD robustness of high-voltage(HV) LDNMOS based on a 0.5 μm 18 V CDMOS process. A two-dimensional(2D) device simulation and a transmission line pulse(TLP) testing were used to analyze the working mechanism and ESD performance of the novel device. Compared with the traditional GG-LDNMOS, the secondary breakdown current(It2) of the proposed device can successfully increase from 1.146 A to 3.169 A with a total width of 50 μm, and ESD current discharge efficiency is improved from 0.459 m A/μm2 to 1.884 m A/μm2. Moreover, due to their different turn-on resistances(Ron), the device with smaller channel length(L) owns a stronger ESD robustness per unit area.     

阴极蒸镀和隔离层对有机发光二极管性能的影响

制备了简单结构的有机发光二极管(OLED)ITO/NPB/Alq3/Al/Ag。实验结果表明,快速蒸镀法制备的Ag阴极越厚,器件性能越差,而慢速蒸镀200nmAg阴极时器件性能也较差。在Alq3与Al阴极之间插入BCP/C60/LiF隔离层后,即使快速蒸镀法制备的Ag厚达280nm,器件的最大电流密度、最大亮度和最大电流效率仍分别高达248.6mA/cm2、5380.7cd/m2和3.52cd/A。隔离层不仅保护NPB和Alq3基本不被玻璃化,还很好地与Alq3和Al阴极匹配,大大提高了器件性能。     

基于R-4B掺杂的黄色OLED器件的制备及性能优化

通过引入新型红光材料R-4B和绿光材料Ir(ppy)2acac混合来实现黄光显示.器件结构为ITO/MoO3(40nm)/NPB(40nm)/TCTA(10nm)/CBP:R-4B(x):Ir(ppy)2acac(8%)(30nm)/BCP(10nm)/Alq3(40nm)/LiF(1nm)/Al(100nm),其中x=1%、2%、3%,通过讨论掺杂浓度对器件性能的影响,得到如下结论:随着红光掺杂比例的增加,红光光强增加,发光颜色由绿色逐渐转变为黄色,但是器件整体的效率、亮度下降.当x=3%时,红光光强不再增加.综合考虑器件性能,发现当红光掺杂比例为2%时,黄色磷光OLED的性能相对最好,色坐标为(0.43 0.53),发光亮度可达4 000cd/m2,在电压为5V时,效率可达32cd/A.     

锌金属配合物BFHQZn的白色有机电致发光器件

利用新型荧光染料2-溴-4-氟苯乙烯-8-羟基喹啉锌(BFHQZn,(E)-2-(2-bromo-4-fluorostyryl)quinolato-Zinc)的电致发光(EL)特性,制备了非掺杂型的有机电致白光器件(WOLED)。器件的结构为ITO/CuPc(10nm)/NPBX(25 nm)/BFHQZn(18 nm)/NPBX(xnm)/BCP(10 nm)/Alq3((47-x)nm)/LiF(0.5 nm)/Al,当x为12时,得到了色度最好和效率最大的WOLED,最大电流效率为1.11 cd/A(at 10 V),最大的亮度为817 cd/m2(at 15 V),当驱动电压从7 V(启亮)升高到15 V(最高亮度)时,器件色坐标由(0.32,038)改变为(0.30,0.28)。     

基于四取代铜酞菁的有机近红外电致磷光器件

制备了结构为ITO/NPB/TPBI:(4-tert)CuPc/BCP/Alq3/Al的近红外(NIR)有机电致发光器件(OLED),器件在室温下的发射峰位于1110nm附近,来源于(4-tert)CuPc分子的磷光发射,器件的最佳掺杂浓度为14wt%。制备了结构为ITO/NPB/TPBI:(4-tert)CuPc/DCJTB/BCP/Alq3/Al的器件,结果表明,DCJTB层的加入没有改变器件的NIR电致发光(EL)峰位置,而器件的NIR发光强度与没有DCJTB层的器件相比,提高了50%左右,这是由于DCJTB向(4-tert)CuPc进行了有效的能量传输。     

TPBTSi配合物的绿色有机发光器件研究

利用2,2,3,3-tetraphenyl-4,4-bisthienylsilole (TPBTSi)作为发光材料,采用真空镀膜的方法制备双层器件ITO/N,bis (1-naphthyl)(1,1'-biphenyl)-4,4'-diamine (NPB)/TPBTSi/Mg:Ag;在此基础上,利用N'-diphenyl-N,N'-tri-(8-hydroxyquinoline) aluminum (Alq3)作为电子传输材料,以TPBTSi为发光层制备了结构为ITO/NPB/TPBTSi/Alq3/Mg:Ag的三层有机发光器件。结果表明,与双层器件相比,三层器件的发光性能得到很大提高,发光光谱谱峰位于516 nm处,即TPBTSi的特征光谱,CIE坐标为(0.275,0.448),且不随电压的改变而变化。在15 V的驱动电压下,器件的最大亮度和流明效率分别为7 032 cd/m2和0.79 lm/W。     

空穴传输层厚度对OLED性能的影响

该文采用聚乙烯基咔唑(PVK)作为空穴传输层,8-羟基喹啉铝(Alq3)作为发光层,制备了结构为ITO/PVK (0~60nm)/Alq3(60 nm)/Mg:Ag/Al的有机发光二极管。通过测试器件的电流-电压-发光亮度特性,研究了空穴传输层厚度对有机发光二极管器件性能的影响,优化了器件功能层的厚度匹配。实验结果表明,有机发光二极管的光电性能与空穴传输层的厚度密切相关,当空穴传输层厚度为15 nm时,有机发光二极管器件具有最低的起亮电压、最高的发光亮度和最大的发光效率。     

基于MCzHQZn的有机电致发光器件

通过结构为ITO/2T-NATA(20nm/NPBx(20nm)/MCzHQZn(30nm)/BCP(10nm)/Alq3(20nm)/LiF(0.5nm)/Al、ITO/2T-NATA(30nm/MCzHQZn(30nm)/BCP(10nm)/Alq3(30nm)/LiF(0.5nm)/Al和ITO/2T-NATA(20nm/MCzHQZn(30nm)/NPBx(16nm)/BCP(10nm)/Alq3(25nm)/LiF(0.5nm)/Al的3组有机电致发光器件(OLED),证明了MCzHQZn既具有空穴传输特性,又具有较好的发光特性。MCzHQZn在器件1中作发光层,器件最大亮度在电压16V时达到3692cd/m2,电压13V时的最大效率为0.90cd/A,发光的峰值波长为564nm;MCzHQZn在器件2中既作发光层又作空穴传输层,器件最大亮度在电压为13V时达到1929cd/m2,电压12V时的最大效率为0.57cd/A,发光的峰值波长也为564nm;MCzHQZn在器件3中作空穴传输层,由NPBx作发光层,器件最大亮度在电压为14V时达到3556cd/m2,电压9V时的最大效率为1.08cd/A,...     

ITO/NPB/Alq_3/LiF/Al电致发光器件光电特性

针对有机电致发光器件发光效率低、稳定性差的问题,设计制备了ITO/NPB/Alq3/LiF/Al多层有机电致发光器件.测试了器件的电流电压特性、器件的亮度电压特性、器件的电致发光光谱.结果表明,当外加电压为16V时,器件的电流达到最大值21.70mA,器件的亮度达到了11 700cd/m2;当外加电压为14 V时,电致发光光谱波峰位于528 nm处,归一化强度最大值为0.522 1a.u.制备的器件电子注入能力、电流和亮度均得到了增强.     

ITO／CuPc／Alq3／Al有机发光二极管的制备与特性测试

利用真空直流溅射和真空蒸镀的方法，制备了结构为ITO／CuPc／Alq3／Al结构的绿光双层有机发光二极管（OLED），对器件的电学特性和电致发光特性进行了测试．结果表明，器件呈现良好的光电性能，发光强度达到6．0×10^5cps，发光光谱在波长510nm时光谱相对强度为2641I／a．u．     

NPB层嵌入MgF_2超薄层对OLED性能的影响

将MgF2超薄层嵌入有机电致发光器件(OLED)的空穴传输层NPB中,制备了结构为ITO/NPB(10nm)/MgF2(xnm)/NPB(20nm)/Alq3(30nm)/Al(30nm)的一系列OLED。测试结果表明,合适厚度的MgF2可有效降低器件启亮电压,提高器件的发光效率。MgF2厚度为0.5nm的器件启亮电压只有2.3V,较未嵌入MgF2器件降低2V;MgF2厚度为1.0nm的器件最大电流效率达到3.93cd/A,最大光功率效率达到1.58lm/W,较未嵌入MgF2器件分别提高95%和110%。