高反射率p-GaN欧姆接触电极

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。     

近红外光谱法测定5-羟基色氨酸的含量

本文利用近红外光谱法建立了5-羟基色氨酸的偏最小二乘(PLS)定量模型。采用相关数法选择波段以及二阶导数、Norris derivative平滑滤波进行数据预处理,所建校正模型的R为0.99907,RMSEC为0.0638,RMSEP为0.0675。经验证模型的预测性能良好,为5-HTP的快速测定提供了一种方法。     

Optimization of gallium nitride-based laser diode through transverse modes analysis

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.     

近红外光谱法测定黄芩提取物中黄芩苷含量

近红外光谱技术(NIR)是近年来快速发展的一种新型光谱分析技术,具有快速、高效、无污染、非破坏性以及实时分析等优点~([1]),已在农业、烟草、石油化工、医药等多领域得到广泛应用.尤其在药物分析方面,体现出近红外光谱分析的巨大潜力~([2]).     

Surface Light Extraction Mapping from Photonic Quasicrystal on Current Two-Dimensional Array of 12-Fold Injected GaN-Based LEDs

A two-dimensional array of dodecagonal photonic quasicrystal （12PQC） is fabricated on the surface of current injected GaN-based LEDs to out-couple guided modes. The spatially-resolved surface light extraction mapping of 12PQC is observed and compared with that of triangular lattice photonic crystal （3PC） by microscopic electrical luminescence and scanning near-field microscopy. The higher enhancement factor of 12PQC is obtained to be larger than that of 3PC. It is shown that 12PQC is more favourable and efficient for light extraction of guided lights.     

Effect of Al Doping in the InGaN/GaN Multiple Quantum Well Light Emitting Diodes Grown by Metalorganic Chemical Vapour Deposition

The effect of Al doping in the GaN layer of InGaN/GaN multiple quantum-well light emitting diodes （LEDs） grown by metalorganic chemical vapour deposition is investigated by using photoluminescence （PL） and highresolution x-ray diffraction. The full width at half maximum of PL of A1 doped LEDs is measured to be about 12nm. The band edge photoluminescence emission intensity is enhanced significantly. In addition, the in-plane compressive strain in the Al-doped LEDs is improved significantly and measured by reciprocal space map. The output power of Al-doped LEDs is 130mW in the case of the induced current of 200mA.     

亚微观团粒的半导体材料

亚微观团粒的半导体,是一种引人注目的材料,因其尺寸小而引起量子效应,表现出非同一般的特性.两个研究小组发表了生成特定大小的硫化铜(CdS)团粒的特殊方法. 截径为1-100nm胶状半导体微粒是一类介于孤立分子和固体之间的新材料,可用来研究由分子态向 大块状态的转变.研究表明,胶体半导体的光学性质与宏观晶体截然不同,它依赖于微粒的大小——即所谓量子尺寸效应.微粒咸小时,电子-空穴对受到局域限制,价带和导带中会产生分立的电子态,有效带隙增大,使材料光谱的吸收边发生向短波移动的“蓝移”,光跃迁的振荡强度减弱,还会出现分立的吸收带;…     

铒注入Si（100）的结晶和掺杂规律研究

研究了Ｓｉ（１００）注入铒后所形成的表面非晶层在不同退火温度下的固相外延结晶以及铒的迁移和掺杂规律。结果表明，表面非晶层先以基体单晶硅为晶种固相外延结晶，铒在晶体－非晶界面偏析，但当铒偏析聚集到一定浓度时则外延结晶停止，剩余损伤层变为多晶结构。在３５０ｋｅＶ的高剂量注入下，再结晶区域内的最大掺杂浓度随退火温度的增加而降低，但对１５０ｋｅＶ的低剂量注入，观察到８５０℃退火温度下掺杂浓度的反常增强。     

Effects of transverse mode coupling and optical confinement factor on gallium-nitride based laser diode

We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm thick n-GaN substrate layer, the maximum optical confinement factor was found to be corresponding to the 5^th order transverse mode, the so-called lasing mode. Moreover, the value of the maximum confinement factor varies periodically when increasing the n-side GaN layer thickness, which simultaneously changes and increases the oscillation mode order of the GaN LD caused by the effects of mode coupling. The effects of the thickness and the average composition of Al in the AlGaN/GaN superlat.tice on the optical confinement factor are also presented. Finally, the mode coupling and optimization of the layers in the GaN-based LD are discussed.     

MOCVD生长InGaN/GaN MQW紫光LED

利用LP－MOCVD系统生长了InGaN/GaN MQW紫光LED外延片，双晶X射线衍射测试获得了2级卫星峰，室温光致发光谱的峰值波长为399.5nm，FWHM为15.5nm，波长均匀性良好。制成的LED管芯，正向电流20mA时，工作电压在4V以下。