共查询到20条相似文献,搜索用时 0 毫秒
1.
L. W. Wu S. J. Chang Y. K. Su T. Y. Tsai T. C. Wen C. H. Kuo W. C. Lai J. K. Sheu J. M. Tsai S. C. Chen B. R. Huang 《Journal of Electronic Materials》2003,32(5):411-414
Nitride-based light-emitting diodes (LEDs) with Si-doped n+-In0.23Ga0.77N/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. 相似文献
2.
首先分析了在制作GaN基LED时,采用干法刻蚀技术会对材料的表面和量子阱有源区造成损伤,影响了GaN基LED的内量子效率。针对这个问题,研究实验采用感应耦合等离子反应刻蚀(ICP-RIE)技术,分别选择了氯气/三氯化硼(Cl2/BCl3)气体体系和氯气/氩气(Cl2/Ar)气体体系,通过优化射频功率、ICP功率、气体流量以及相应的真空度,得到了良好的刻蚀端面,对于材料造成的损伤较低,得到更好的I-V特性。实验结果表明,采用低损伤的偏压功率刻蚀后制作的LED器件,出光功率提升一倍以上,同时采用Cl2/Ar气体体系,改善了器件的I-V特性,有效提高了LED的出光效率。 相似文献
3.
4.
Hao Wu Xuanwu Kang Yingkui Zheng Ke Wei Lin Zhang Xinyu Liu Guoqi Zhang 《半导体学报》2022,43(6):062803-1-062803-8
In this work, the optimization of reverse leakage current (IR) and turn-on voltage (VT) in recess-free AlGaN/GaN Schottky barrier diodes (SBDs) was achieved by substituting the Ni/Au anode with TiN anode. To explain this phenomenon, the current transport mechanism was investigated by temperature-dependent current–voltage (I–V) characteristics. For forward bias, the current is dominated by the thermionic emission (TE) mechanisms for both devices. Besides, the presence of inhomogeneity of the Schottky barrier height (qφb) is proved by the linear relationship between qφb and ideality factor. For reverse bias, the current is dominated by two different mechanisms at high temperature and low temperature, respectively. At high temperatures, the Poole–Frenkel emission (PFE) induced by nitrogen-vacancy (VN) is responsible for the high IR in Ni/Au anode. For TiN anode, the IR is dominated by the PFE from threading dislocation (TD), which can be attributed to the decrease of VN due to the suppression of N diffusion at the interface of Schottky contact. At low temperatures, the IR of both diodes is dominated by Fowler–Nordheim (FN) tunneling. However, the VN donor enhances the electric field in the barrier layer, thus causing a higher IR in Ni/Au anode than TiN anode, as confirmed by the modified FN model. 相似文献
5.
A. Matoussi T. Boufaden S. Guermazi Y. Mlik B. El Jani A. Toureille 《Journal of Electronic Materials》2005,34(7):1059-1064
In this article, we report the electron beam-induced current (EBIC) measurements in a GaN Schottky diode performed in the
line-scan configuration. A theoretical model with an extended generation source was used to accurately extract some minority
carrier transport properties of the unintentionally doped n-GaN layer. The minority hole diffusion length is found to increase
from ∼0.35 μm near the junction to ∼1.74 μm at the bulk regions. This change is attributed to an increase of the carrier lifetime
caused by the polarization effects, which are preponderant in this component. For depth distances exceeding 0.65 μm, it is
shown that the measured current is produced by the reabsorption recombination radiation process. This corresponds to an absorption
coefficient of 0.178 μm−1, in good agreement with the optical absorption measurement. 相似文献
6.
The material and electrical properties of GaN-based light-emitting diodes (LEDs) grown on wet-etched stripe-patterned substrates
were investigated. Footprint-like patterns, located directly above the inclined groove sidewalls, were found on the as-grown
LED surface. Cross-sectional transmission electron microscopy (TEM) showed that ‘tumor’-like structures with poor crystal
quality were initiated on the inclined sidewalls, seeding dislocation bundles in the subsequently grown crystal. The high
dislocation density slowed down the growth above the inclined sidewall, resulting in the uneven morphology. The fabricated
devices showed over 30% enhancement in light output power as a result of improvements in both internal and extraction efficiencies. 相似文献
7.
针对GaN基发光二极管中p-GaN与透明导电薄膜ITO之间的接触进行研究,尝试找出透明导电层ITO的优化制程条件。将在不同氧流量、ITO厚度及退火温度下制备的透明电极ITO薄膜应用于GaN基发光二极管,来增加电流扩展,减小ITO与p-GaN欧姆接触电阻,降低LED工作电压及提高透过率、增强LED发光亮度。将ITO薄膜应用于218μm×363μm GaN基发光二极管LED,分析其在20 mA工作电流条件下正向电压和光输出功率的变化,在优化条件下制得的蓝光LED在直流电流20 mA下的正向电压3.23 V,光输出效率为23.25 mW。 相似文献
8.
利用发光光谱估计AlGaInP LED结温的新方法 总被引:1,自引:1,他引:0
针对常用的正向电压法接触式测量以及峰 值波长法在结温估计前需要定标、峰值波 长与结温近似成线性关系等问题,提出了一种方便和精确的发光二极管(LED)结温非接触测 量方法。通过对 Varshni式和Bose-Einstein式的比较分析,得到Varshni式中常数项α、β与Bose-Einstein式中aB、θD的关 系式,从而建立起峰值波长与结温的非线性关系,同时对四元系材料AlGaInP LED的禁带宽 度公式进行推导,实现利用发光光谱非接触式估计结温的方法。本文方法无需结温估计前的 定标系统,避免由仪器结 构等带来的误差,提高了精度。实验结果表明,利用本文方法推导的Varshni公式中ΔEg(T)=Eg(0)-Eg(T)的理 论值和实验值最大误差不超过0.003eV,进而 估计的结 温 与实际的结温能够较好吻合,估计误差为2K,且低于由峰值波长法得到的估计误差6K。 相似文献
9.
Craig G. Moe Mathew C. Schmidt Hisashi Masui Arpan Chakraborty Kenneth Vampola Scott Newman Brendan Moran Likun Shen Tom Mates Stacia Keller Steven P. Denbaars David Emerson 《Journal of Electronic Materials》2006,35(4):750-753
Deep ultraviolet light-emitting diode structures with a peak wavelength of 275 nm, as well as individual AlGaN:Mg layers,
were grown by metalorganic chemical vapor deposition on (0001) silicon carbide. Control of the Mg profile in the devices reduced
unwanted Mg-related emission at 320 nm to 1/224th of that emitted at the peak wavelength. An additional peak at 410 nm was
observed to be related to oxygen incorporation in the film and confirmed with secondary ion mass spectroscopy (SIMS). Also
investigated in an effort to improve hole injection were aluminum content, layer thickness, V/III ratio, activation temperature,
and properties of the GaN:Mg contact layer and transparent contact metal stack. By optimizing this and other layers of the
device, output powers of 0.84 mW at 1.3 A were obtained from packaged devices, with forward voltages as low as 4.9 V at 20
mA. 相似文献
10.
Wonseok Lee Jae Limb Jae-Hyun Ryou Dongwon Yoo Theodore Chung Russell D. Dupuis 《Journal of Electronic Materials》2006,35(4):587-591
We investigated the electrical and structural qualities of Mg-doped p-type GaN layers grown under different growth conditions
by metalorganic chemical vapor deposition (MOCVD). Lower 300 K free-hole concentrations and rough surfaces were observed by
reducing the growth temperature from 1,040°C to 930°C. The hole concentration, mobility, and electrical resistivity were improved
slightly for Mg-doped GaN layers grown at 930°C with a lower growth rate, and also an improved surface morphology was observed.
In0.25Ga0.75N/GaN multiple-quantum-well light emitting diodes (LEDs) with p-GaN layers grown under different conditions were also studied.
It was found from photoluminescence studies that the optical and structural properties of the multiple quantum wells in the
LED structure were improved by reducing the growth temperature of the p-layer due to a reduced detrimental thermal annealing
effect of the active region during the GaN:Mg p-layer growth. No significant difference in the photoluminescence intensity
depending on the growth time of the p-GaN layer was observed. However, it was also found that the electroluminescence (EL)
intensity was higher for LEDs having p-GaN layers with a lower growth rate. Further improvement of the p-GaN layer crystalline
and structural quality may be required for the optimization of the EL properties of long-wavelength (∼540 nm) green LEDs. 相似文献
11.
简要介绍了晶圆键合技术在发光二极管(LED)应用中的研究背景,分别论述了常用的黏合剂键合技术、金属键合技术和直接键合技术在高亮度垂直LED制备中的研究现状,包括它们的材料组成和作用、工艺步骤和参数以及优缺点.其中,黏合剂键合是一种低温键合技术,且易于应用、成本低、引入应力小,但可靠性较差;金属键合技术能提供高热导、高电导的稳定键合界面,与后续工艺兼容性好,但键合温度高,引入应力大,易造成晶圆损伤;表面活化直接键合技术能实现室温键合,降低由于不同材料间热失配带来的负面影响,但键合良率有待提高. 相似文献
12.
T. C. Wen S. J. Chang Y. K. Su L. W. Wu C. H. Kuo W. C. Lai J. K. Sheu T. Y. Tsai 《Journal of Electronic Materials》2003,32(5):419-422
High-quality InGaN/GaN multiple-quantum well (MQW) light-emitting diode (LED) structures were prepared by a temperature-ramping
method during metal-organic chemical-vapor deposition (MOCVD) growth. Two photoluminescence (PL) peaks, one originating from
well-sensitive emission and one originating from an InGaN quasi-wetting layer on the GaN-barrier surface, were observed at
room temperature (RT). The observation of high-order double-crystal x-ray diffraction (DCXRD) satellite peaks indicates that
the interfaces between InGaN-well layers and GaN-barrier layers were not degraded as we increased the growth temperature of
the GaN-barrier layers. With a 20-mA and 160-mA current injection, it was found that the output power could reach 2.2 mW and
8.9 mW, respectively. Furthermore, it was found that the reliability of the fabricated green LEDs prepared by temperature
ramping was also reasonably good. 相似文献
13.
高反射性电流阻挡层用于提高InGaN/GaN发光二极管的光输出功率 总被引:1,自引:0,他引:1
由SiO2/TiO2分布布拉格反射镜(DBR)和Al镜组成的混合式反射电流阻挡层用于提高InGaN/GaN发光二极管的光输出功率。混合式反射电流阻挡层不仅增强了电流扩展效应而且有效的将射向p金属电极的光子反射防止其对p电极焊点附近光子的吸收。实验结果表明,淀积在p-GaN上1.5个周期的SiO2/TiO2DBR和Al镜在455nm垂直入射时的反射率高达97.8%。在20mA的工作电流下,与没有电流阻挡层的发光二极管相比,生长1.5对SiO2/TiO2 DBR和Al镜作为电流阻挡层的发光二极管的光输出功率提高了12.5%,且光输出功率的分布更加均匀。 相似文献
14.
为了研究一种无荧光粉的单芯片白光发光二极管(LED)的光电性质,实际测量了它的升温电致发光光谱和升温电流-电压(I-V)特性,并测量了相似结构的蓝光LED以作对比。实验发现白光LED的电致发光光谱中有一个与有源区中的深能级相关的较宽的长波长发光峰,根据这个发光峰的强度与温度之间的依赖关系,通过数据拟合,得到了深能级的平均激活能,约为199 meV。由于有源区中存在大量深能级,也对白光LED的I-V特性产生一定影响,有源区中的深能级成为额外的载流子源,使白光LED的I-V特性表现出独特的性质。 相似文献
15.
Zhou Xin Gu Shulin Zhu Shunming Ye Jiandong Liu Wei Liu Songmin Hu Liqun Zheng Youdou Zhang Rong Shi Yi 《半导体学报》2006,27(2):249-253
报道了n-ZnO/p-GaN异质结构发光二极管的制备及其发光特性.采用金属有机气相外延技术在Mg掺杂p型GaN衬底上外延n型ZnO薄膜以形成p-n结.实验发现在一定配比的HF酸和NH4Cl溶液中,腐蚀深度和腐蚀时间呈线性关系,并且二氧化硅和ZnO的腐蚀速率得到很好的控制,这对器件制备的可靠性非常重要.电流-电压(I-V)特性测试显示该器件结构具有明显的整流特性.室温下,在正反向偏压状态下都可用肉眼观察到电致发光现象.同时,通过与光致发光谱进行比较,对电致发光谱中发光峰的起源和发光机制进行了探讨. 相似文献
16.
报道了n-ZnO/p-GaN异质结构发光二极管的制备及其发光特性.采用金属有机气相外延技术在Mg掺杂p型GaN衬底上外延n型ZnO薄膜以形成p-n结.实验发现在一定配比的HF酸和NH4Cl溶液中,腐蚀深度和腐蚀时间呈线性关系,并且二氧化硅和ZnO的腐蚀速率得到很好的控制,这对器件制备的可靠性非常重要.电流-电压(I-V)特性测试显示该器件结构具有明显的整流特性.室温下,在正反向偏压状态下都可用肉眼观察到电致发光现象.同时,通过与光致发光谱进行比较,对电致发光谱中发光峰的起源和发光机制进行了探讨. 相似文献
17.
In this work, metallic bonding in GaN-based vertical light-emitting diode (VLED) is systematically characterized by using combined methodology of transmission Kikuchi diffraction (TKD) and energy dispersive X-ray spectroscopy (EDS) in a scanning electron microscope (SEM). SEM-based TKD with EDS identifies chemical composition, grain morphology, orientation, and phases at metallic bonding, while transmission electron microscopy (TEM) provides nanoscale characteristics of metallic diffusion bonding, and its interface-related defects and nano-twinned boundaries. Our results from SEM-TKD and TEM techniques provide unparalleled insight into the metallic bonding, and its future optimization. 相似文献
18.
Lateral current spreading in the 4H-SiC Schottky barrier diode(SBD)chip is investigated.The 4H-SiC SBD chips with the same vertical parameters are simulated and fabricated.The results indicate that there is a fixed spreading resistance at on-state in current spreading region for a specific chip.The linear specific spreading resistance at the on-state is calculated to be 8.6 Ω/cm in the fabricated chips.The proportion of the lateral spreading current in total forward current(Psp)is related to an-ode voltage and the chip area.Psp is increased with the increase in the anode voltage during initial on-state and then tends to a stable value.The stable values of Psp of the two fabricated chips are 32%and 54%.Combined with theoretical analysis,the pro-portion of the terminal region and scribing trench in a whole chip(Ksp)is also calculated and compared with Psp.The Ksp val-ues of the two fabricated chips are calculated to be 31.94%and 57.75%.The values of Ksp and Psp are close with each other in a specific chip.The calculated Ksp can be used to predict that when the chip area of SiC SBD becomes larger than 0.5 cm2,the value of Psp would be lower than 10%. 相似文献
19.
This work describes a comparison of current density–voltage (J–V) and capacitance–voltage (C–V) properties measured as a function of temperature; deep trap properties are measured by deep level transient spectroscopy (DLTS) of Schottky diodes fabricated on n-type gallium nitride (GaN grown by metal organic vapor phase epitaxy (MOVPE). Unexpected behavior in the standard Richardson plot was observed in the temperature range 165–480 K, reflecting a range of Schottky barrier heights and a variation of ideality factor. This was explained by applying a Gaussian spatial distribution of barrier heights across the Schottky diode. C–V measurements were carried out in the temperature range 165–480 K to compare the temperature dependence of the barrier height with those obtained by the Gaussian distribution method. DLTS and high-resolution Laplace DLTS (LDLTS) show a majority carrier peak centered at 450 K. 相似文献