MOCVD生长AlGaN/GaN/Si(111)异质结材料

利用MOCVD在Si(111)衬底上生长了无裂纹的GaN外延薄膜和AlGaN/GaN异质结构。通过优化Si衬底的浸润处理时间、AlN层厚度等参数获得了无裂纹的GaN外延薄膜,研究了SiN缓冲层和插入层厚度对AlGaN/GaN异质结电学性质的影响,2DEG的迁移率和面密度分别达到1410cm2/V.s和1.16×1013cm-2。     

氮化对蓝宝石衬底上AlGaN/GaN异质结材料性能的影响

研究了不同氮化条件对蓝宝石衬底上生长的AlGaN/GaN异质结材料特性的影响。研究表明,随着氮化过程NH3流量的增大,GaN外延层的晶体质量得到了改善,GaN内应力释放,但是AlGaN/GaN异质结构中二维电子气的迁移率有所恶化。讨论了上述现象出现的原因。     

氮化对蓝宝石衬底上AlGaN/GaN异质结

研究了不同氮化条件对蓝宝石衬底上生长的AlGaN/GaN异质结材料特性的影响。研究表明,随着氮化过程NH₃流量的增大,GaN外延层的晶体质量得到了改善,GaN内应力释放,但是AlGaN/GaN异质结构中二维电子气的迁移率有所恶化。讨论了上述现象出现的原因。     

76.2mm Si基AlGaN/GaN HEMT

<正>南京电子器件研究所采用含有双AlGaN过渡层的材料结构在76.2 mm(3英寸)Si衬底上外延生长了厚度超过2μm的AlGaN/GaN HEMT材料(图1),材料表面光滑、无裂纹。通过外延材料结构和生长条     

不同AlGaN层厚度的AlGaN/GaN高电子迁移率晶体管的静态特性

利用金属有机化合物气相外延技术研究了AlGaN/GaN高电子迁移率晶体管(HEMT)结构的外延生长及器件制作,重点比较了具有不同AlGaN层厚度的HEMT器件的静态特性.实验发现具有较薄AlGaN隔离层的结构表现出较好的器件特性.栅长为1μm的器件获得了650mA/mm的最大饱和电流密度和100mS/mm的最大跨导.     

应用于微波通信系统新型器件GaN HEMT研究

通过自洽求解一维泊松方程,计算了应用于微波通信系统的非故意掺杂AlGaN/AlN/GaN高电子迁移率晶体管(HEMT)的外延层结构参数对器件的二维电子气(2DEG)浓度,跨导等性能的影响.通过理论分析并结合TCAD软件最终确定AlGaN/AlN/GaN HEMT的最佳外延层结构.对栅长0.3 μm和栅宽100 μm的器件仿真结果表明,器件的最大跨导为418 mS/mm,器件的最大电流密度为2 300 mA/mm,性能良好.     

Ka波段AlGaN/GaN HEMT的研制

为了提高AlGaN/GaN HEMT的频率,采用了缩小源漏间距、优化栅结构和外围结构等措施设计了器件结构,并基于国内的GaN外延片和工艺完成了器件制备.测试表明所研制的AlGaN/GaN HEMT可以满足Ka波段应用.其中2×75μm栅宽AlGaN/GaN HEMT在30V漏压下的截止频率为32GHz,最大振荡频率为1...     

低温生长n型氮化镓插入层提高LED抗静电能力

在这篇论文里,我们通过在InGaN/GaN 多量子阱和n型氮化镓层中间插入一层低温生长的n型氮化镓显著提高了LED的抗静电能力。通过引入低温生长的氮化镓插入层使得LED抗击穿电压超过4000V的良品率从9.9%提升到74.7%。低温生长的氮化镓插入层作为后续生长的多量子阱的缓冲层,释放了量子阱中的应力并且改善了量子阱的界面质量。另外,我们证明了在氮气气氛下生长低温氮化镓插入层对于LED抗静电能力的改善要强于氢气气氛,同时也进一步证明低温插入层对量子阱中应力的释放有利于提高LED的抗静电能力。光电测试结果表明,在引入低温nGaN缓冲层后,LED的电学特性并没有衰退,并且LED的光输出功率提高了13.9%。     

InGaN/GaN和InGaN/AlGaN多量子阱中应变对光致发光特性的影响

对蓝宝石衬底上的InGaN/GaN和InGaN/AlGaN多量子阱结构和经激光剥离去除衬底的InGaN/GaN和InGaN/AlGaN多量子阱结构薄膜样品,进行了光致发光谱、高分辨XRD和喇曼光谱测量.PL测量结果表明,相对于带有蓝宝石衬底的样品,InGaN/GaN多量子阱薄膜样品的PL谱峰值波长发生较小的蓝移,而InGaN/AlGaN多量子阱薄膜样品的PL谱峰值波长发生明显的红移;喇曼光谱的结果表明,激光剥离前后E2模的峰值从569.1减少到567.5cm-1.这说明激光剥离去除衬底使得外延层整体的压应力得到部分释放,但InGaN/GaN与InGaN/AlGaN多量子阱结构中阱层InGaN的应力发生了不同的变化.XRD的结果证实了这一结论.     

InGaN/GaN和InGaN/AlGaN多量子阱中应变对光致发光特性的影响

对蓝宝石衬底上的InGaN/GaN和InGaN/AlGaN多量子阱结构和经激光剥离去除衬底的InGaN/GaN和InGaN/AlGaN多量子阱结构薄膜样品,进行了光致发光谱、高分辨XRD和喇曼光谱测量.PL测量结果表明,相对于带有蓝宝石衬底的样品,InGaN/GaN多量子阱薄膜样品的PL谱峰值波长发生较小的蓝移,而InGaN/AlGaN多量子阱薄膜样品的PL谱峰值波长发生明显的红移;喇曼光谱的结果表明,激光剥离前后E2模的峰值从569.1减少到567.5cm-1.这说明激光剥离去除衬底使得外延层整体的压应力得到部分释放,但InGaN/GaN与InGaN/AlGaN多量子阱结构中阱层InGaN的应力发生了不同的变化.XRD的结果证实了这一结论.     

Improved III-nitrides based light-emitting diodes anti-electrostatic discharge capacity with an AlGaN/GaN stack insert layer

Through insertion of an AlGaN/GaN stack between the u-GaN and n-GaN of GaN-based light-emitting diodes(LEDs),the strain in the epilayer was increased,the dislocation density was reduced.GaN-based LEDs with different Al compositions were compared.6.8%Al composition in the stacks showed the highest electrostatic discharge(ESD) endurance ability at the human body mode up to 6000 V and the pass yield exceeded 95%.     

Improvement in the characteristics of GaN-based light-emitting diodes by inserting AlGaN-GaN short-period superlattices in GaN underlayers

We report the influence of short-period superlattice (SPSL)-inserted structures in the underlying undoped GaN on the characteristics of GaN-based light-emitting diodes (LEDs). The measurements of current-voltage (I-V) curves indicate that GaN-based LEDs having pseudomorphic Al/sub 0.3/Ga/sub 0.7/N(2 nm)-GaN(2 nm) SPSL-inserted structures exhibit improvements in device characteristics with the best LED being inserted with two sets of five-pair Al/sub 0.3/Ga/sub 0.7/N(2 nm)-GaN(2 nm) SPSL structure. Based upon the results of etch pit counts, double-crystal X-ray diffraction measurements and transmission electron microscopic observations of the GaN-based LEDs, it was found that the Al/sub 0.3/Ga/sub 0.7/N(2 nm)-GaN(2 nm) SPSL-inserted structures tended to serve as threading dislocation filters in the LEDs so that the improved I-V characteristics were achieved.     

Improved ⅢI-nitrides based light-emitting diodes anti-electrostatic discharge capacity with an AlGaN/GaN stack insert layer

Through insertion of an AlGaN/GaN stack between the u-GaN and n-GaN of GaN-based light-emitting diodes (LEDs),the strain in the epilayer was increased,the dislocation density was reduced.GaN-based LEDs with different Al compositions were compared.6.8％ A1 composition in the stacks showed the highest electrostatic discharge (ESD) endurance ability at the human body mode up to 6000 V and the pass yield exceeded 95％.     

Improvement of the performance of GaN-based LEDs grown on sapphire substrates patterned by wet and ICP etching

Sapphire substrates patterned by a selective chemical wet and an inductively coupled plasma (ICP) etching technique was proposed to improve the performance of GaN-based light-emitting diodes (LEDs). GaN-based LEDs were fabricated on sapphire substrates through metal organic chemical vapor deposition (MOCVD). The LEDs fabricated on the patterned substrates exhibit improved device performance compared with the conventional LED fabricated on planar substrates when growth and device fabricating conditions were the same. The light output powers of the LEDs fabricated on wet-patterned and ICP-patterned substrates were about 37% and 17% higher than that of LEDs on planar substrates at an injection current of 20 mA, respectively. The enhancement is attributable to the combination of the improvement of GaN-based epilayers quality and the improvement of the light extraction efficiency.     

Nitride-Based LEDs With Phosphoric Acid Etched Undercut Sidewalls

We propose a simple defect-selective wet etching method to form oblique sidewalls for GaN-based epitaxial layers with phosphoric acid. Using the same defect-selective wet etching, we also prepared GaN-based light-emitting diodes (LEDs) with undercut sidewalls. Compared with conventional LEDs with vertical sidewalls, it was found that output intensity of the LEDs prepared by defect-selective wet etching was 30% higher.      

High Brightness GaN-Based Light-Emitting Diodes

This paper reviews our recent progress of GaN-based high brightness light-emitting diodes (LEDs). Firstly, by adopting chemical wet etching patterned sapphire substrates in GaN-based LEDs, not only could increase the extraction quantum efficiency, but also improve the internal quantum efficiency. Secondly, we present a high light-extraction 465-nm GaN-based vertical light-emitting diode structure with double diffuse surfaces. The external quantum efficiency was demonstrated to be about 40%. The high performance LED was achieved mainly due to the strong guided-light scattering efficiency while employing double diffuse surfaces     

Nano-Processing Techniques Applied in GaN-Based Light-Emitting Devices With Self-Assembly Ni Nano-Masks

We have developed a simple method to fabricate nanoscale masks by using self-assembly Ni clusters formed through a rapid thermal annealing (RTA) process. The density and dimensions of the Ni nano-masks could be precisely controlled. The nano-masks were successfully applied to GaN-based light-emitting diodes (LEDs) with nano-roughened surface, GaN nanorods, and GaN-based nanorod LEDs to enhance light output power or change structure properties. The GaN-based LED with nano-roughened surface by Ni nano-masks and excimer laser etching has increased 55% light output at 20 mA when compared to that without the nano-roughened process. The GaN nanorods fabricated by the Ni nano-masks and ICP-RIE dry etching showed 3.5 times over the as-grown sample in photoluminescence (PL) intensity. The GaN-based nanorod LEDs assisted by photo-enhanced chemical (PEC) wet oxidation process were also demonstrated. The electroluminescence (EL) intensity of the GaN-based nanorod LED with PEC was about 1.76 times that of the as-grown LED. The fabrication, structure properties, physical features, and the optical and electrical properties of the fabricated devices will be discussed.     

Improved light extraction efficiency of GaN-based light emitting diodes using one and two interfaces of ITO/ZnO layer texturing

Light extraction efficiency of GaN-based light emitting diodes (LEDs) has improved significantly by using ITO/ZnO layer texturing. We have deliberately designed and successfully fabricated GaN-based LEDs having one and two interfaces of ITO/ZnO layer texturing in the device structure. It was found that the light extraction efficiencies of one and two interfaces of ITO/ZnO-layer texturing LEDs were 22.29% and 35.54% at 20 mA of current injection, respectively. Creating the chances of multiple light scattering at more than one interface is playing a major role to enhance light output power of the device. The source of the enhanced light output power is also discussed.     

Gallium-nitride-based materials for blue to ultravioletoptoelectronics devices

Breakthroughs in materials growth have enabled extremely high-efficiency blue and green GaN light emitting diodes (LEDs) to be achieved for the first time. Blue LEDs with external quantum efficiency exceeding 9% have enabled hybrid GaN/phosphor white lamp LEDs. GaN LEDs complete the primary color spectrum and have enabled bright and reliable full-color solid-state displays to be realized. Recently, room-temperature operation of continuous wave current-injection blue-violet lasers emitting at 417 nm has further increased the possible applications for GaN-based opto-electronic devices. In this paper, we review the key technologies for GaN-based materials and devices. Developments in the methods for thin-film deposition by metalorganic chemical vapor deposition and molecular beam epitaxy and resulting film properties are highlighted     

在侧壁形成导热膜的GaN基发光二极管

研制了一种在侧壁形成导热膜的GaN基发光二极管(LED),其中导热层由氮氧化铝形成,导热层外再覆盖一保护层,保护层选自氧化物、氮化物或氟化物.对LED进行电流加速老化实验,分析输出功率随老化时间的变化关系,可以看到侧壁形成导热膜的GaN基LED的输出功率衰减缓慢.实验表明由于氮氧化铝膜具有良好的导热性,其可以有效地耗散发光部分产生的热量,因此在器件侧壁形成AlON导热膜可以改善GaN基LED的输出特性并提高器件的可靠性.