Research of the theory and key technology for fabrication of the GaN-base bule violet laser diodes

宽禁带Ⅲ－Ⅴ族GaN基半导体材料在发光二极管、激光器、光电探测器以及高温、高频和大功率电子器件等方面有着诱人的应用前景和巨大的市场需求，是近年来光电子材料领域研究的热门课题。特别是发光波段在400～410nm的GaN基蓝紫光激光器是高密度光存储系统中最有希望的光源，因此制作蓝紫光短波长的激光器一直是人们研究的焦点，但GaN基激光器材料的生长和器件的制备方面还存在一些困难，特别是GaN基材料的P型掺杂、厚且无裂的AlGaN材料生长、高质量的P型GaN欧姆接触等。 本文针对以上一些问题并结合GaN基激光器的研制工作开展了一系列的相关的研究，比如：一维光场模拟、相关材料的生长和低P型欧姆接触的研究...GaN based Ⅲ-Ⅴ nitrides as a wide band gap semiconductor has played a key role in the research field of opoelectronic materials and devices, due to its promising appliciations and great potential market in LEDs,short-wavelength laser diodes,ultraviolet detectors, high temperature and high power electronic devices.Especially, GaN based bule-violet laser diodes with wavelength from 400 nm to 410 nm i...学位：理学博士院系专业：物理与机电工程学院物理学系_凝聚态物理学号：1812005140302

Reduce Ohmic Contact Resistance to p-GaN Using InGaN/AlGaN Superlattice

提出用P-IngAn/AlgAn超晶格作为P-gAn的接触层来获得低阻欧姆接触。通过一维薛定谔方程和泊松方程的自洽求解,得到了在极化效应影响下的IngAn/AlgAn,IngAn/gAn和gAn/AlgAn三种超晶格中Mg杂质离化率的空间分布。计算发现IngAn/AlgAn超晶格具有最高的Mg杂质离化率及最佳的空穴局域作用。最后,利用P-IngAn/AlgAn超晶格实验上实现了比接触电阻率为7.27x10-5Ω.CM2的良好欧姆接触。In order to achieve a smaller Ohmic contact resistance,p-InGaN/AlGaN superlattice was proposed to be used as the cap-layer of p-GaN.By making use the self consistent Poisson-Schrodinger calculations,obtained were the distributions of the ionization rate of Mg dopant in InGaN/AlGaN,InGaN/GaN and GaN/AlGaN superlattices when taking into account of the effect of polarization.It was found that the InGaN/AlGaN superlattice cap-layer had the largest ionization rate of Mg and the best confinement of the holes.Finally,the specific contact resistance of 7.27×10-5 Ω·cm2 was realized.国家自然科学基金项目(60276029);国家“863”计划项目(2004AA311020;2006AA032409);福建省科技项目(2006H0092;A0210006;2005HZ1018

Optimization Electrode of GaN-Based Light-Emitting Diode

针对以蓝宝石为衬底的GaN基发光二极管出现的电流扩展不均的问题,采用有限元方法建立了GaN基发光二极管的三维网络模型,并对四种常见结构的器件进行数值模拟,发现影响二极管电流的因素不仅与发光二极管电极的位置有关,而且依赖于器件的结构参数。以电流扩展不均为指标确定出这四种器件中最佳的电极位置分布,同时对最佳电极位置分布的器件进行了结构参数优化,结果表明当p型金属层方块电阻与n型GaN的方块电阻接近时,电流扩展均匀性最好,且p-GaN的接触电阻和厚度越小,电流扩展越不均匀。A 3D networks model of GaN-based LED on sapphire substrate was built by finite element analysis to simulate the non-uniformity current spreading.Analog modeling was done on the four normal device structures,it was found that the factors effected the current of LED were the position of electrode and the parameters of device structure.Considering the practical structures of GaN-based LED,four LED designs were modeled and the optimal electrode distribution was obtained,meanwhile the structure parameters were optimized.It reveals that the smaller contact resistances and the thickness of p-GaN are,the more non-uniformity of current distribution is.国家自然科学基金(60276029);; 国家863计划(2004AA311020和2006AA032409);; 福建省科技项目和基金(2006H0092,A0210006,2005HZ1018

The Research of Low Ohmic Contact Resistance to p-GaN

利用低压MOCVD系统,获得了p-GaN和p-InGaN/GaN超晶格结构2种材料,用圆形传输线模型(CTLM)测量了它们的比接触电阻率,并对表面处理、金属沉积和合金化处理的工艺条件进行了优化,得到了550℃、O2氛围下合金30min的最佳条件,获得最低的比接触电阻率为1.99×10-4Ω.cm2。P-GaN bulk material and p-InGaN/GaN superlattice used as p-contact layer are grown by low pressure metal organic chemical vapor deposition(LP-MOCVD),and their specific contact resistivity(SCR)is measured by circular transmission line model(CTLM).Meanwhile,surface pretreatment,metal deposion and annealing processes of ohmic contact on p-InGaN/GaN superlattice are optimized,and the best result with the SCR of 1.99×10-4 Ω·cm2 is achieved after annealing at 550 ℃ for 30 min in oxygen.国家自然科学基金资助项目(60276029);; 国家“863”计划资助项目(2004AA311020);; 福建省科技项目(2005HZ1018

GaN-based Blue Light-emitting Diodes with a Nano-roughened ITO Surface

将氧化铟锡(ITO)生长于氮化镓基蓝色发光二极管的出光台面上(p型GaN台面),用非平面化处理的方法制作出ITO井状结构,研制出非平面化型氧化铟锡-氮化镓基蓝色发光二极管(LED),获得了高的出光效率。结果表明,在20 mA工作电流下,该蓝色发光二极管的出光光强是平整的普通ITO-GaN基LED的1.35倍。Indium-tin-oxide(ITO) material was grown on the plane of a new type GaN-based light emitting diodes(LEDs).A pillar or well structure arranged periodically in the plane were successfully fabricated,which obtained high light-extracted efficiency.It is found that the output power of the new type LEDs under 20mA current is 1.35 times higher than the normal ITO-GaN-based LED.国家自然科学基金项目(60276029);; 国家“863”计划项目(2004AA311020,2006AA03Z409);; 福建省科技项目(2006H0092,A0210006,2005HZ1018