基于PIN结构的Rubrene/C70太阳能电池的性能研究

实验制备了ITO/V₂O₅/Rubrene/C₇₀:Rub rene/C₇₀/BCP/Al的PIN结构有机太阳能电池(OSC),其中 Rubrene、Rubrene:C₇₀和C₇₀分别作为P、I和N层。通过改变I层厚度,研究了I 层对OSC性能的影响及作用机理。实验显示,I层厚为5nm时器件的功率转换效率η达到最大值为1.580%,同时 获得了较大的短路电流密度Jsc为4.365mA· cm－2;相对PN结构器件,功率转化效率η短路电流密度Jsc和填充因子FF分别提 高了40.3%、29.7%和8.2%。我们认为,I层中激子分离效率的提高导 致了器件性能的改善。     

ZnO缓冲层改善Rubrene/C70有机太阳能电池的性能

通过制备结构为ITO/ZnO/C₇₀ /Rubrene/MoO₃/Al 的有机太阳能电池(OSCs),研究了ZnO作为阴极 修饰层对Rubrene/C70有机太阳能电池性能的改善。同时通过 优化ZnO的厚度研究了ZnO的工作机理。 从实验结果可以看出,随着ZnO厚度的变化,器件的短路电流密度(J_sc)、开路电压(V_oc)、填充因子 (FF)、光电转换效率(PCE)和串联电阻(R_s)等性能参数呈现出了规律 性变化,当ZnO层厚度比较 薄时,器件PCE随着厚度的增加不断增大,当ZnO层厚度为53nm时,器件PCE达到最高为1.13%, 对应的J_sc、V_oc、FF分别为2.82mA·cm－2、0. 84V、45.86%,R_s为66.2Ω·cm²,当ZnO层厚度继续增 加时,器件PCE开始减小。对比没有ZnO阴极修饰层,器件最优时 的Jsc、V_oc、FF和PCE 分别提高了49%、17%,R_s降低了56%。     

WO3对Rubrene/C70有机太阳能电池性能的改善

研究了WO₃对Rubrene/C₇₀有机太阳能电池 (OSCs)性能的 改善,制备了结构为ITO/WO₃/Rubrene/C₇₀/BCP/Al的OSCs,其中WO₃插入在I TO和Rubrene中间作为阳极修饰层。通过优化WO₃的厚度,研究了WO₃对OSCs性能的改善及其作用机理。实验发现,器件的短路电流Jsc、开路电压V_oc、 填充因子(FF)、光电转换效率(PCE)和串联电阻Rs等性能参数随WO₃厚度的变化呈规律性变化;当 WO₃厚度小于80 nm时,器件PCE随着厚度的增加不断增大;当W O ₃厚大于80 nm时,器件PCE随着厚度的 增加不断减小;当WO₃厚度为80 nm 时,器件PCE达到最高为1.03%, 相应的J sc、V_oc、FF分别为2.81mA·cm－2、 0.83V、43.85%,Rs为45.3Ω·cm²,对比没有WO₃修饰层, 器件的J_sc、V_oc、FF和PCE分别提高了31%、137%、17%,Rs降低了33%。     

基于PIN结构的Rubrene/C_(70)太阳能电池的性能研究

实验制备了ITO/V2O5/Rubrene/C70:Rubrene/C70/BCP/Al的PIN结构有机太阳能电池(OSC),其中Rubrene、Rubrene:C70和C70分别作为P、I和N层。通过改变I层厚度,研究了I层对OSC性能的影响及作用机理。实验显示,I层厚为5nm时器件的功率转换效率η达到最大值为1.580%,同时获得了较大的短路电流密度Jsc为4.365mA·cm-2;相对PN结构器件,功率转化效率η短路电流密度Jsc和填充因子FF分别提高了40.3%、29.7%和8.2%。我们认为,I层中激子分离效率的提高导致了器件性能的改善。     

低温处理的TiO2纳米颗粒薄膜作为缓冲层的有机光伏电池

通过溶胶凝胶法(sol-gel)合成了TiO₂纳米颗 粒(NPs),制备了结构为 ITO/PEDOT:PSS/P3HT:PCBM/TiO₂/Al的有机太阳能电池(OSC)器件。通过优化阴极缓冲 层TiO₂NPs的 热处理温度,考察了温度以及溶剂对TiO₂NPs薄膜的光学性能、形貌结构和电学 性能的影响,并研究了其对OSC性能的影响及作用机理。实验发现,TiO₂NPs处理温度 为80℃时,器件 的效率达到了2.52%。相对于参比器件,器件的光电转换效率(PCE) 、填充因子(FF)分别提高了60%、64.7%。     

热处理对Rubrene/C70有机太阳能电池性能的改善

制备了ITO/MoO3(6nm)/Rubrene(30nm)/C70(30nm)/BCP(6nm)/Al(150nm)的PN结构和ITO/MoO3(5nm)/Rubrene(25nm)/Rubrene:C70(5nm)/C70(25nm)/BCP(6nm)/Al(150nm)的PIN结构有机太阳能电池(OSCs)。通过对两种器件进行热处理,研究热处理对OSCs性能的影响。实验表明,在热处理后,PN结构和PIN结构器件的短路电流密度分别达到了3.526mA·cm-2和5.413mA·cm-2,功率转换效率分别达到了1.43%和2.09%。与未经过热处理的器件相比,PN结构和PIN结构器件的短路电流密度、填充因子、功率转换效率分别提高了19.0%、7.1%、28.3%和4.8%、20%、24.1%。可见,热处理可以提高Rubrene/C70OSCs的性能。     

Bathocuproine作为缓冲层改善Rubrene/C70太阳能电池的性能

制备了结构为ITO/Rubrene/C70/BCP/Al的双层有机太阳能电池(OSCs),通过优化缓冲层BCP的厚度研究了BCP对OSCs性能的影响及其作用机理。实验发现,BCP厚为6nm时,器件的效率最高达到1.78%,同时获得了较大的开路电压0.901V。相对于没有缓冲层,器件的效率、短路电流、开路电压和填充因子分别提高了432.9%、74.8%、95.4%和55.5%。     

基于CdSe/ZnS和Alq3的白光量子点LED的研究

采用CdSe/ZnS红光量子点(QD),利用旋涂和真 空蒸镀工艺制备了结构为ITO/TPD+PVK/QDs/Alq₃/LiF/Al的量 子点发光器件(QD-LED),并对器件的发光性能做了测试。研究了ITO表面处理、TPD空穴 传输层和QD发光层的厚 度对QD-LED性能的影响,并通过调整QD发光层和Alq₃电子传输层的 厚度,制备了可用于照明 的白光QD-LED。实验结果表明,ITO的表面处理可有效降低器件的开启电压,开启 电压从9V降到7V左右; TPD空穴传输层和QD发光层的厚度对器件的电流密度和发光亮度有较大的影响,而Alq₃电 子传输层和QD发光层 的合理配比可以混合出较高色温的白光。通过优化器件各参数,当TPD和PVK质量比为5∶1、QD度为1.0mg/ml和 Alq₃厚为60nm时,制备的器件在15V电压 时发光效率达到了1500c d/m²,色坐标为(0.3628,0.3796) ,显色指数为88.1。     

MoO3修饰氧化石墨烯作为空穴注入层影响研究

研究了MoO₃修饰氧化石墨烯(GO)作为空穴注入层的影响。采用旋涂的方法制备了GO, 再真空蒸镀修饰层MoO₃,得到了空穴注入能力强和透过率高的复合薄膜。MoO₃的厚分 别采用0、3、5和8nm。通过优化MoO₃的厚度发现,当MoO₃的厚为5nm时,复合薄膜 的透过率达到最大值,在 550nm的光波长下透光率为88%,且此时采用 复合薄膜作为空穴注入层制备的结构为 ITO/GO/MoO₃(5nm)/NPB(40nm)/Alq₃(40nm)/LiF(1nm)/Al(100nm)的有机电致发光器件(OLED)性能 最佳。通过对OLED进一步的优化,改变Alq₃的厚度,分别取50、60和70nm,测量其电压 、电流、亮度、色坐标和电致发光(EL)光谱等参数发现,当Alq₃的厚为50nm时器件性能最 佳。最终制备了结构为ITO/GO/MoO₃(5nm)/NPB(50nm)/Alq₃(50nm)/LiF(1nm)/Al(100 nm)的OLED,在电压为10V时,最大电流效率达到5.87cd/A,与GO单独作为空穴注入层制备的器件相比,提高了50%。     

α-IGZO薄膜场效应晶体管的光敏特性

通过掩膜板制备源漏电极 的方法,以非晶铟-镓-锌氧化物(α-IGZO)为有源层,制备了结构为ITO/SiO₂(400nm)/α-IGZO(50nm)/Al 的底栅顶接触型(BGTC)光敏薄膜场效应晶体管(TFT) 并研究了其光敏特性。实验发现,在蒸镀Al电极作为源极和漏极,再在 空气中及350℃的温度下退火1h后,器件的阈值电压Vt h为15.0V,在栅源偏压VGS=30V时其有效场效应迁移率 为0.57cm²/Vs,表现出良好的晶体管特性。当用强度为8.1mW/cm²的白光照射时,器件表现出明显 的光敏特 性,其Vth下降为－15.0V,在源漏电压VDS=20V且VGS=30V时其有 效场效应迁移率上升为1.34cm²/Vs, 在VGS=2.5V时其“明/暗”电流比达到一极大值,响应 率达到1.11A/W,并具有良好的时间响应特性。     

Li_2分子A~1Σ_u~+→X~1Σ_g~+LIF和b~3Ⅱ_u→X~1Σ_g~+CIF发射光谱研究

用632.8nm CW激光获得了Li_2分子A~1∑_u~+(v′=15,J′=2)→X~1∑_g~+(v″=1～13,J″=1,3)R、P支双线LIF光谱。同时用光谱分析及碰撞动力学研究识别出另一支单线序列光谱来自b~3Ⅱ_u(v_b=21,N_b=1)→X~1∑_g~+(v″=3～6,J″=1)CIF发射。     

一种针对超宽带标准的CMOS Gm-C低通滤波器

采用TSMC 0.18µm CMOS工艺实现了一种针对超宽带标准的264MHz低通滤波器。该4阶滤波器由两个二阶滤波器级联而成,相对于传统的二阶Gm-C滤波器设计,本文提出的二阶拓扑结构十分简单有效,节约了1个跨导单元,3个共模反馈网络,2个电容。因此芯片功耗和芯片面积大大降低,其他指标并无牺牲。测试表明该滤波器增益-0.5dB,频率响应实测结果与仿真吻合良好,芯片面积为〖0.06mm〗^2,远小于同类设计,在1.8V电源电压下,电流消耗为3mA。     

Photoluminescence characteristics of GaN/lnGaN/GaN quantum wells

Photoluminescence (PL) characteristics of GaN/lnGaN/GaN single quantum wells (QWs) and an InGaN/GaN single heterojunction were studied using continuous wave (CW) and pulsed photoluminescence in both edge and surface emitting configurations. Samples were grown on c-plane sapphire substrates by atmospheric pressure metalorganic chemical vapor deposition (MOCVD). Room temperature and 77K PL measurements were performed using a CW Ar-ion laser (305 nm) and a frequency tripled (280 nm), pulsed, mode-locked Ti: sapphire laser. CW PL emission spectra from the quantum wells (24, 30, 80Å) were all blue shifted with respect to the reference sample. The difference (i. e., the blue shift) between the measured value of peak emission energy from the QW and the band-edge emission from the reference sample was attributed to quantum size effects, and to strain arising due to a significant lattice mismatch between InGaN and GaN. In addition, stimulated emission was observed from an InGaN/GaN single heterojunction in the edge and surface emitting configu-ration at 77K. The narrowing of emission spectra, the nonlinear dependence of output emission intensity on input power density, and the observation of a strongly polarized output are presented.     

MOCVD生长Al0.48Ga0.52N/Al0.54Ga0.36N多量子阱的结构和光学特性

采用金属有机物化学气相淀积(MOCVD)技术,在蓝宝石衬底上生长了Al0.48Ga0.52N/Al0.54Ga0.36N多量子阱(MQWs)结构。通过双晶X射线衍射(DCXRD)、原子力显微镜(AFM)和阴极荧光(CL)等测试技术,分别对样品的结构和光学特性进行了表征。在DCXRD图谱中,可以观察到明显的MQWs衍射卫星峰,通过拟和,MQWs结构中阱和垒的厚度分别为2.1和9.4nm,Al组分分别为0.48和0.54。在AFM表面形貌图上,可以观察到清晰的台阶流,表明MQWs获得了二维生长;与此同时,MQWs结构存在一些裂缝,主要原因为AlGaNMQWs结构和下层GaN层间存在很大的应力。CL测试表明,AlGaNMQWs结构的发光波长为295nm,处于深紫外波段,同时观察到处于蓝光、绿光波段的缺陷发光。     

Metamaterial inspired quad band circularly polarized antenna for WLAN/ISM/Bluetooth/WiMAX and satellite communication applications

A CPW fed metamaterial inspired Quadband circularly polarized antenna is presented in this article. The proposed antenna consists of defected ground structure with a radiating stub, which is at opposite side of the feedline. A waveguide mode of analysis is carried out for split ring resonator (SRR) and complimentary split ring resonator (CSRR) to enhance the properties of metamaterials. The proposed antenna analysis is taken iteration wise and used FR-4 Material as the substrate material with Ɛ_r = 4.4 and analysed using ANSYS electromagnetic desktop. The designed antenna projecting the peak gain of 4.8 dB and it is working in the application bands of WLAN/ISM/Bluetooth at 2.4 GHz, 5.8 GHz and 3.35 WiMAX band, X-band downlink satellite communication system (7.25–7.75 GHz) and ITU band (8–8.5 GHz) with fractional bandwidth of about 70%. Proposed antenna exhibits circular polarization at 2.39–2.55 GHz, 3.05–3.1 GHz, 4–5 GHz and 6.3–6.64 GHz respectively. To know the signal integrity of the antenna, time domain analysis is carried out for identical antennas in two conditions (face to face and side by side) with the help of CST microwave studio. The designed antenna showing excellent correlation in measurements with respect to simulation results.     

Systematic Synthesis of Compressive VDTA-Based T-T Filter with Orthogonal Control of fo and Q

Based on sixteen nullor-mirror models of the voltage differencing transconductance amplifier (VDTA) and port admittance matrices of the tow-Thomas (T-T) filter with orthogonal control between the characteristic frequency (f_o) and figure of merit (Q), two different categories of the voltage-mode and transconductance-mode T-T filters are synthesized by the means of the nodal admittance matrix (NAM) expansion method. The category A filter that employs two compressive VDTAs and two grounded capacitors includes four structures, and the category B filter that uses two compressive VDTAs, two grounded capacitors, and one grounded resistor, also includes four structures. These circuits are suitable for integrated circuit manufacture, and their parameters f_o and Q can be orthogonally adjusted with varying the bias currents of VDTAs. After the paper and pencil test is completed, the computer analyses, including alternating current (AC), parameter sweep, Monte Carlo (MC), and noise analyses, are performed to support the synthesis approach.     

Contactless electroreflectance study of a GaAIAs/lnGaAs/ GaAs/GaAIAs step quantum well structure

Using contactless electroreflectance at 300 and 77K, we have studied the inter-subband transitions from a GaAlAs/InGaAs/GaAs/GaALAs step quantum well structure (small well inside a large well) consisting of two layers A (In_xGa_1−xAs) and B (GaAs) with widths L_A and L_B, respectively, bounded by two thick barrier regions of Ga_x Al_yAs. By comparison of the observed spectral features with an envelope function calculation, including the effects of strain, we have been able to characterize the potential profile of the structure, i.e., L_A, L_B, x, and y. There is very good agreement between experiment and the intended materials param-eters. Such configurations are of considerable importance since (a) they form the basis for pseudomorphic high electron mobility transistors, and (b) also have applications in optoelectronics due to their large Stark shifts.     

Annealing effect on the metal gate effective work function modulation for the Al/TiN/SiO2/p-Si structure

In this work, the thermal annealing effect on the metal gate effective work function (EWF) modulation for the Al/TiN/SiO₂/p-Si(1 0 0) structure was investigated. Compared with the sample of TiN/SiO₂/p-Si(1 0 0) structure, for the sample additionally capped with Al the flat band voltage has a very obvious shift as large as 0.54 V to the negative direction after forming gas annealing. It is also revealed that the thermal budget can effectively influence both the EWF of the gate electrode and the thickness of the gate dielectric layer when a post annealing at 600 °C with different soak times was applied to the samples with Al cap. Material characterization indicates that the diffusion of Al and the formation of Al oxide during annealing should be responsible for all the phenomena. The interface trap density Dit calculated from the high-frequency C-V and the laser-assisted high-frequency C-V curves show that the introduction of Al does not cause reliability problem in the Al/TiN/SiO₂/p-Si structure.     

60/102/204混合细胞自动机的可逆性分析

细胞自动机的理论研究主要包括细胞自动机的分析和综合两个方面,而细胞自动机的可逆性分析则是细胞自动机分析中的核心问题。60/102/204混合细胞自动机作为一类重要的细胞自动机,利用矩阵分析方法将其状态转移表示为矩阵方程,从而分析其可逆性、可逆细胞自动机的数目和可逆细胞自动机的构造。60/102/204混合细胞自动机可逆性分析对于其在密码学、通信和测试等领域的应用具有重要意义。     

InGaN/GaN LEDs with a Si-doped InGaN/GaN short-period superlattice tunneling contact layer

Nitride-based light-emitting diodes (LEDs) with Si-doped n⁺-In_0.23Ga_0.77N/GaN short-period superlattice (SPS) tunneling contact top layer were fabricated. It was found that although the measured specific-contact resistance is around 1 × 10⁻² Ω-cm² for samples with an SPS tunneling contact layer, the measured specific-contact resistance is around 1.5×10⁰ Ω-cm² for samples without an SPS tunneling contact layer. Furthermore, it was found that one could lower the LED-operation voltage from 3.75 V to 3.4 V by introducing the SPS structure. It was also found that the LED-operation voltage is almost independent of the CP₂Mg flow rate when we grow the underneath p-type GaN layer. The LED-output intensity was also found to be larger for samples with the SPS structure.