ITO界面调制层对GZO电极LED器件性能的影响

采用磁控溅射制备GZO和具有ITO界面调控层的GZO(ITO/GZO)透明导电薄膜作为大功率LED的电流扩散层,对比研究界面调控层对LED器件性能的影响。研究结果表明,ITO/GZO薄膜的透过率在可见光区达80%以上,退火后的ITO/GZO薄膜有较低的电阻率(1.15×10^-3 Ω·cm)。ITO调控层的介入能够调制GZO表面粗糙度,有利于改善LED外量子效率,降低GZO/p-GaN界面的接触势垒,提高LED器件的光电性 能。通过ITO界面调控后,LED器件20 mA驱动电流下的工作电压从9.5 V降低为6.8 V,发光强度从245 mcd 升到297 mcd,提高了20%;驱动电流为35 mA时,其发光强度从340.5 mcd 升到511 mcd,提高了50%。     

AgO_x界面插入层对GZO电极LED器件性能的影响

采用磁控溅射的方法在p-GaN上制备了GZO透明导电薄膜,通过在p-GaN和GZO界面之间插入AgOx薄层来改善LED器件的接触性能。研究结果表明:氮气退火后,采用界面插入层的AgOx/GZO薄膜电阻率为5.8×10-4Ω.cm,在可见光的透过率超过80%。AgOx界面插入层有效地降低了GZO与p-GaN之间的接触势垒,表现出良好的欧姆接触特性,同时使LED器件的光电性能获得了显著的提高。在50 mA的注入电流下,相比于常规的GZO电极LED器件,AgOx/GZO电极LED器件的正向电压由9.68 V降至6.92 V,而发光强度提高了13.5%。     

基于PTCDA的有机/无机光敏二极管结构优化

以p型硅和苝四甲酸二酐(perylene-3,4,9,10-tetracarboxylic acid dianhydride,PTCDA)为异质结,梳状金(Au)薄膜作为顶电极和光入射窗口制备了光敏二极管。研究表明,PTCDA的厚度和Au电极的厚度对光敏二极管的光响应度有很大的影响。对比不同PTCDA厚度的器件性能,在PTCDA厚度为100 nm时,光响应度最高达到0.3 A/W。进而采用最优化的100 nm厚的PTCDA薄膜制备硅基光敏二极管,对比不同Au电极厚度的器件性能。在Au厚度为20 nm时,器件的光响应度达到最优化的0.5 A/W。     

柔性SrTiO_3/Ag/SrTiO_3复合结构透明导电薄膜的制备和性能研究

为获得高性能的柔性透明导电薄膜,采用磁控溅射技术在柔性PC衬底上制备出了STO(30nm)/Ag/STO(30nm)复合结构透明导电薄膜.分别对不同中间Ag层厚度薄膜的结构、光学和电学性质进行了研究.研究发现:随着中间Ag层厚度的增加,可见光区的平均透过率先增大后减小,电阻率和方块电阻持续减小;当中间Ag层厚度为11nm时,复合结构透明导电薄膜具有最佳的品质因子为14.23×10~(-3)Ω~(-1),此时,其可见光区平均透过率为82%,方块电阻为9.2Ω/sq..     

生长温度对Ga掺杂ZnO薄膜光电性能的影响

在不同衬底温度(室温~750 ℃)条件下,采用脉冲激光沉积(PLD)方法在石英玻璃和单晶硅(111)衬底上制备了Ga掺杂ZnO(GZO)薄膜。结果显示:衬底温度的变化导致衬底表面吸附原子扩散速率和脱附速率的不同,从而导致合成薄膜结晶质量的差异,衬底温度450 ℃时制备的GZO薄膜具有最好的结晶特性;GZO薄膜中载流子浓度随衬底温度升高而单调减小的现象与GZO薄膜中的本征缺陷密切相关,晶界散射强度的变化导致迁移率出现先增大后减小的趋势,衬底温度450 ℃时制备的GZO薄膜具有最小的电阻率~0.02 Ω·cm;随着衬底温度的升高,薄膜载流子浓度的单调减小导致了薄膜光学带隙变窄,所有合成样品的平均可见光透过率均达到85%以上。采用PLD方法制备GZO薄膜,衬底温度的改变可以对薄膜的光电性能起到调制作用。     

表面化学处理和退火对p-GaN/ZnO:Ga接触特性的影响

ZnO∶Ga(GZO)透明电极沉积在p-GaN表面,用作透明电流扩展层。直接沉积在p-GaN上的p-GaN/GZO存在较大的势垒,容易形成肖特基接触,而良好的欧姆接触对功率LED器件至关重要。为了降低接触势垒,采用盐酸和氢氧化钠溶液对GaN表面进行去氧化层处理,并对p-GaN/GZO进行退火处理,研究表面处理和退火对p-GaN/GZO接触特性的影响。研究表明:碱性溶液处理有利于降低接触势垒;退火处理后,接触势垒略有增加。     

基于Ce^3+∶YAG透明陶瓷的大功率LED和LD照明原型器件的发光性能:厚度和表面粗糙度的影响EI北大核心CSCD

采用高温真空烧结技术制备了0.5%Ce∶Y 3Al5O12(简称Ce∶YAG)透明荧光陶瓷,在透射模式下分别采用大功率蓝光发光二极管(LED)芯片(3.2 V×0.3 A)激发和LD蓝光光源(0.8 W,1.6 W)激发,系统研究了陶瓷厚度(0.3~2.3 mm)和表面粗糙度(322.86 nm,9.79 nm)等对照明原型器件的色温、显色指数和光电转换效率等发光性能的影响。结果表明,陶瓷表面有一定粗糙度可使原型器件的发光性能整体提高,其中用粗糙度为322.86 nm的Ce∶YAG透明陶瓷组装的原型器件分别获得了93.6 lm/W(蓝光LED激发)和178.5 lm/W(蓝光LD激发)的高光电转换效率。研究表明,通过调节Ce∶YAG透明陶瓷的厚度和表面状态,可有效提升高功率密度固态照明器件的发光性能。     

激光溅射沉积制备的ZnO:Ga薄膜表面形貌分析

薄膜表面形貌定量研究有助于薄膜生长机理的认识.研究的薄膜是用激光脉冲沉积法(PLD)制备的ZnO:Ga(GZO)透明导电薄膜.由于GZO薄膜的生长是在远离平衡态情况下实现的,具备自仿射分形特征,可以用高度-高度相关函数进行描述.通过对用原子力显微镜(AFM)获得的表面高度数据进行相关运算,定量地分析了PLD制备的GZO...     

基于PTCDA的有机/无机光敏二极管结构优化

以p型硅和苝四甲酸二酐 （perylene-3,4,9,10-tetracarboxylic acid dianhydride,PTCDA）为异质结,梳状金（Au）薄膜作为顶电极和光入射窗口制备了光敏二极管。研究表明,PTCDA的厚度和Au电极的厚度对光敏二极管的光响应度有很大的影响。对比不同PTCDA厚度的器件性能,在PTCDA厚度为100 nm时,光响应度最高达到0.3 A/W。进而采用最优化的100 nm厚的PTCDA薄膜制备硅基光敏二极管,对比不同Au电极厚度的器件性能。在Au厚度为20 nm时,器件的光响应度达到最优化的0.5 A/W。     

基于MoO_3/Au/MoO_3透明电极的有机太阳能电池

以透明导电薄膜Mo O3/Au/Mo O3代替铟锡氧化物(ITO)作为有机太阳能电池(OSCs)的阳极,研究了一系列结构为Mo O3/Au/Mo O3的透明电极和Mo O3(y nm)/Au(x nm)/Mo O3(y nm)/Cu Pc(25 nm)/C60(40nm)/BCP(8 nm)/Al(100 nm)的有机太阳能电池。研究表明,Mo O3/Au/Mo O3电极的光电特性可通过改变各层薄膜厚度加以调控,在Mo O3薄膜厚度为40 nm、Au薄膜厚度为10 nm时性能最优,且以该薄膜为电极的有机太阳能电池器件的性能接近于电极为ITO的有机太阳能电池器件。     

Effect of Au interlayer thickness on the structural,electrical, and optical properties of GZO/Au/GZO multilayers

We report on the structural, electrical, and optical properties of Ga-doped ZnO/Au/Ga-doped ZnO (GZO/Au/GZO) multilayers as a function of Au interlayer thickness. Aggregated Au islands formed a continuous film as the thickness of the Au interlayer increased from 3 to 12 nm. Consequently, the sheet resistance, resistivity, and optical transmittance decreased with increasing Au interlayer thickness compared to a GZO single layer. However, a relatively high peak transmittance and a high figure of merit were obtained for an Au interlayer thickness of 9 nm. These results showed that the characteristics of GZO/Au/GZO multilayers could be improved by inserting an Au interlayer of optimized thickness. In addition, it indicated that the GZO/Au/GZO multilayer is the most promising candidates for indium free transparent conducting oxides (TCOs).     

Effect of GZO thickness and annealing temperature on the structural,electrical and optical properties of GZO/Ag/GZO sandwich films

The GZO/Ag/GZO sandwich films were deposited on glass substrates by RF magnetron sputtering of Ga-doped ZnO (GZO) and ion-beam sputtering of Ag at room temperature. The effect of GZO thickness and annealing temperature on the structural, electrical and optical properties of these sandwich films was investigated. The microstructures of the films were studied by X-ray diffraction (XRD). X-ray diffraction measurements indicate that the GZO layers in the sandwich films are polycrystalline with the ZnO hexagonal structure and have a preferred orientation with the c-axis perpendicular to the substrates. For the sandwich film with upper and under GZO thickness of 40 and 30 nm, respectively, it owns the maximum figure of merit of 5.3 × 10⁻² Ω⁻¹ with a resistivity of 5.6 × 10⁻⁵ Ω cm and an average transmittance of 90.7%. The electrical property of the sandwich films is improved by post annealing in vacuum. Comparing with the as-deposited sandwich film, the film annealed in vacuum has a remarkable 42.8% decrease in resistivity. The sandwich film annealed at the temperature of 350 °C in vacuum shows a sheet resistance of 5 Ω/sq and a transmittance of 92.7%, and the figure of merit achieved is 9.3 × 10⁻² Ω⁻¹.     

Effect of graphene/ZnO hybrid transparent electrode on characteristics of GaN light-emitting diodes

In order to reduce the Schottky barrier height and sheet resistance between graphene(Gr) and the p-GaN layers in GaN-based light-emitting diodes(LEDs), conductive transparent thin films with large work function are required to be inserted between Gr and p-GaN layers. In the present work, three kinds of transparent conductive oxide(TCO) zinc oxide(ZnO) films, Al-, Ga-, and In-doped ZnO(AZO, GZO, and IZO), are introduced as a bridge layer between Gr and p-GaN,respectively. The influence of different combinations of Gr/ZnO hybrid transparent conducting layers(TCLs) on the optical and thermal characteristics of the GaN-LED was investigated by the finite element method through COMSOL software. It is found that both the TCL transmittance and the surface temperature of the LED chip reduce with the increase in Gr and ZnO thickness. In order to get the transmittance of the Gr/ZnO hybrid TCL higher than 80%, the appropriate combination of Gr/ZnO compound electrode should be a single layer of Gr with ZnO no thicker than 400 nm(1 L Gr/400-nm ZnO),2 L Gr/300-nm ZnO, 3 L Gr/200-nm ZnO, or 4 L Gr/100-nm ZnO. The LEDs with hybrid TCLs consisting of 1 L Gr/300-nm AZO, 2 L Gr/300-nm GZO, and 2 L Gr/300-nm IZO have good performance, among which the one with 1 L Gr/300-nm GZO has the best thermal property. Typically, the temperature of LEDs with 1 L Gr/300-nm GZO hybrid TCLs will drop by about 7 K compared with that of the LEDs with a TCL without ZnO film.     

Effect of thickness on the stability of transparent conducting impurity‐doped ZnO thin films in a high humidity environment

The resistivity of transparent conducting Al‐ and Ga‐doped ZnO (AZO and GZO) thin films prepared with a thickness in the range from 20 to 200 nm on glass substrates at a temperature below 200 °C was found to increase with exposure time when tested in a high humidity environment (air at 90% relative humidity and 60 °C). The resistivity stability (resistivity increase) was considerably affected by the thin film thickness. In particular, thin films with a thickness below about 50 nm were very unstable. The increase in resistivity is interpreted as carrier transport being dominated by grain boundary scattering resulting from the trapping of free electrons due to oxygen adsorption on the grain boundary surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation of Ga-doped ZnO films by pulsed dc magnetron sputtering with cylindrical rotating target for thin film solar cell applications

Applicability of Ga-doped ZnO (GZO) films for thin film solar cells (TFSCs) was investigated by preparing GZO films via pulsed dc magnetron sputtering (PDMS) with rotating target. The GZO films showed improved crystallinity and increasing degree of Ga doping with increasing thickness to a limit of 1000 nm. The films also fulfilled requirements for the transparent electrodes of TFSCs in terms of electrical and optical properties. Moreover, the films exhibited good texturing potential based on etching studies with diluted HCl, which yielded an improved light trapping capability without significant degradation in electrical propreties. It is therefore suggested that the surface-textured GZO films prepared via PDMS and etching are promising candidates for indium-free transparent electrodes for TFSCs.     

基于金属掺杂ITO透明导电层的紫外LED制备

为降低ITO薄膜对紫外波段的光吸收,制备低电压高功率的紫外LED,研究了一种基于金属掺杂ITO透明导电层的365 nm紫外LED的制备工艺。利用1 cm厚的石英片生长了不同厚度ITO薄膜以及在ITO上掺杂不同金属的新型薄膜,并研究了在不同的退火条件下这种薄膜的电阻和透过率,分析了掺杂金属ITO薄膜的带隙变化。将这种掺杂的ITO薄膜生长在365 nm外延片上并完成电极生长,制备成14 mil×28 mil的正装LED芯片。利用电致发光（EL）设备对LED光电性能进行测试并对比。实验结果表明:掺Al金属的ITO薄膜能够相对ITO薄膜的带隙提高0.15 eV。在600℃退火后,方块电阻降低6.2 Ω/□,透过率在356 nm处达到90.8%。在120 mA注入电流下,365 nm LED的电压降低0.3 V,功率提高14.7%。ITO薄膜掺金属能够影响薄膜带隙,改变紫光LED光电性能。     

Characteristic difference between ITO/ZrCu and ITO/Ag bi-layer films as transparent electrodes deposited on PET substrate

The metallic-glass film of ZrCu layer deposited by co-sputtering was utilized as the metallic layer in the bi-layer structure transparent conductive electrode of ITO/ZrCu (IZC) deposited on the PET substrate using magnetron sputtering at room temperature. In addition, the pure Ag metal layer was applied in the same structure of transparent conductive film, ITO/Ag, in comparison with the IZC film. The ZrCu layer could form a continuous and smooth film in thickness lower than 6 nm, compared with the island structure of pure Ag layer of the same thickness. The 30 nm ITO/3 nm ZrCu films could show the optical transmittance of 73% at 550 nm wavelength. The 30 nm ITO/12 nm ZrCu films could show the better sheet resistance of 20 Ω/sq, but it was still worse than that of the ITO/Ag films. It was suggested that an alloy system with lower resistivity and negative mixing heat between atoms might be another way to form a continuous layer in thickness lower than 6 nm for metal film.