排序方式: 共有103条查询结果,搜索用时 15 毫秒
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研究用于GaN基大功率倒装焊(Flip-chip)紫光LED(UV-LED)的高反射率p型欧姆接触的电学和光学性能。用磁控溅射的方法在GaN基LED外延片表面沉积了不同厚度Ag,Al,Au和Pd四种金属,测量了样品的反射率和透射率。结合同步辐射高强度X射线衍射和AFM对金属薄膜的晶体结构进行分析,并对表面形貌进行了观测,对由金属薄膜构成的多层膜结构及其对光反射率的作用机理进行了研究。测量结果表明,在入射光波长为400nm时,Ni/Au/Ag和Ni/Au/Al电极的反射率比Ni/Au的反射率提高了三倍。同时与p-GaN有良好的欧姆接触特性。 相似文献
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根据光学薄膜原理计算了GaN/Ti/Ag、GaN/Al和GaN/Ni/Au/Ti/Ag、GaN/Ni/Au/Al多层电极结构的反射率,得出Ag基和Al基反射电极均能在全角范围内提供较高的反射率。实验测量结果表明,反射率能高于80%的Ag基反射电极,具有低欧姆接触的电学特性。并将GaN/Ni/Au/Ti/Ag多层反射电极应用在上下电极结构的GaN基LED中。实验上采用两步合金法获得了低接触电阻、高反射率的电极结构,并引入Ni/Au覆盖层克服了Ag高温时的团聚和氧化现象。解决了Ag电极的稳定性问题,显著地提高了LED的出光效率,成功制备了具有上下电极结构的GaN基LED管芯。 相似文献
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We investigate the transverse mode pattern in GaN quantum-well (QW) laser diode (LD) by numerical calculation.We optimize the current GaN LD structure by varying the n-GaN layer thickness.The n-type GaN layer is an important factor to determine the optical mode.Finally,we discuss the lasing performance of the GaN LD based on the transverse optical modes. 相似文献
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高亮度白光LED用外延片的新进展 总被引:5,自引:0,他引:5
文章首先介绍了发光二极管(LED)的内量子效率、外量子效率的基本概念和提高量子效率的基本方法,接着对LED外延的结构和方法做了简要介绍.文章的第三和第四部分则着重介绍了提高内、外量子效率的外延方法,这些方法包括外延结构的优化,侧向外延生长,SiC和GaN衬底的生长,AIInGaN四元系有源区生长,非极性面、半极性面的外延,表面粗化结构生长,图形化二次外延结构.图形化蓝宝石衬底上的外延,提高载流子注入效率的结构和组分设计.文章的第五部分则介绍了基于可靠性和成本考虑的其他新型外延结构,第六部分介绍了提高LED可靠性的外延方法.最后得出结论:采用非极性面的GaN衬底,生长优化的LED结构,并结合光子晶体技术,可望取得突破性进展. 相似文献
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Comparative Characterization of InGaN/GaN Multiple Quantum Wells by Transmission Electron Microscopy, X-Ray Diffraction and Rutherford Backscattering 下载免费PDF全文
The composition, elastic strain and structural defects of InCaN/CaN multiple quantum wells (MQWs) are comparatively investigated by using x-ray diffraction (XRD), transmission electron microscopy and Rutherford backscattering/channelling. The InGaN well layers are fully strained on CaN, i.e. the degree of relaxation is zero. The multilayered structure has a clear defined periodic thickness and abrupt interfaces. The In composition is deduced by XRD simulation. We show how the periodic structure, the In composition, the strain status and the crystalline quality of the InGaN/GaN MQ, Ws can be determined and cross-checked by various techniques. 相似文献
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Nonpolar a-plane light-emitting diode with an in-situ SiNx interlayer on r-plane sapphire grown by metal-organic chemical vapour deposition 下载免费PDF全文
We report on the growth and fabrication of nonpolar a-plane light emitting diodes with an in-situ SiNx interlayer grown between the undoped a-plane GaN buffer and Si-doped GaN layer. X-ray diffraction shows that the crystalline quality of the GaN buffer layer is greatly improved with the introduction of the SiNx interlayer. The electrical properties are also improved. For example, electron mobility and sheet resistance are reduced from high resistance to 31.6 cm2/(V·s) and 460 Ω/口 respectively. Owing to the significant effect of the SiNx interlayer, a-plane LEDs are realized. Electroluminescence of a nonpolar a-plane light-emitting diode with a wavelength of 488nm is demonstrated. The emission peak remains constant when the injection current increases to over 20 mA. 相似文献
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Optical and Electronic Properties of InGaN/GaN Multi—Quantum—Wells Near—Ultraviolet Lighting—Emitting—Diodes Grown by Low—Pressure Metalorganic Vapour Phase Epitaxy 下载免费PDF全文
The near-ultraviolet lighting-emitting-diodes (UV-LEDs) with the InGaN/GaN multi-quantum-well (MQW) structure were grown by low-pressure metalorganic vapour phase epitaxy. The double crystal x-ray diffraction revealed a distinct second-order satellite peak. The near-ultraviolet InGaN/GaN MQW LEDs have been successfully fabricated to emit at 401.2nm with narrow FWHM of 14.3nm and the forward voltage of 3.6 V at 20 mA injection current at room temperature. With increasing forward current from l 0 mA to 50 mA, the redshift of the peak wavelength was observed due to the band-gap narrowing caused by heat generation. 相似文献
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研究了在MBE系统中,GaAs(001)表面的氮化过程。GaAs(001)表面直接和间接地暴露在等离子体激发的N2气流下。两种氮化过程显示了完全不同的表面氮化结果。在打开N2发生器挡板的情况下,氮化导致GaAs(001)表面损伤,并且形成多晶结构。当增加N2气压时,损伤变得更严重。但是,在关闭N2发生器挡板的情况下,在500℃下,经过氮化将观察到(3×3)再构的RHEED花样,表面仍保持原子级的平整度。上述结果表明,不开N2发生器挡板,低温(500℃下)氮化将在GaN外延生长之前形成平整的薄层c-GaN。 相似文献
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