硅基GaN外延膜生长与LED性能提升研究

发布时间：2018-05-29 05:13

本文选题：硅衬底 + 图形衬底　；参考：《南昌大学》2014年博士论文

【摘要】：以GaN基LED芯片为基础的固态照明器件具有发光效率高，寿命长，响应速度快，发光强度随电流和脉冲宽度近线性变化，能在剧烈振动和恶劣环境下工作，不含环境有害物质等优点，成为新一代通用照明灯具的首选。随着研究的深入和产业的发展，GaN基发光二极管的材料生长和器件制造技术已经取得了长足进步，器件效率和可靠性也有显著提升；特别是硅衬底GaN LED外延技术和芯片制造技术的成功实施，芯片成本进一步下降，加速了LED灯全面取代白炽灯和荧光灯进入通用照明领域的进程。在此背景下，本文开展了对硅衬底GaN基材料和器件生长的研究。论文首先对Al合金掩膜微图形化Si(111)衬底上GaN材料的侧向外延生长进行了研究；然后，研究了同温cap层和cap层厚度对绿光InGaN/GaN MQWs LEDs量子阱材料质量和芯片发光性能的影响，以及湿法表面粗化对蓝光LED芯片取光效率的提升作用；最后，对硅衬底GaN垂直结构大功率发光二极管的可靠性进行了研究分析。通过上述研究，本论文取得了以下主要结果： 1.提出了用于硅衬底GaN材料选区外延生长的Al-Si合金掩膜技术。通过在Si(111)衬底表面蒸镀150金属Al，经光刻工艺制作Al金属图形，然后高温1200℃下进行合金扩散，获得了Al-Si合金掩膜的图形化硅衬底。实验表明，在Al-Si合金掩膜区不会生长GaN，因此，Al-Si合金技术是Si衬底上选区外延生长GaN材料的一种有效掩膜方法。 2.通过优化Al-Si合金条形掩膜参数和GaN外延生长条件，成功地在Al-Si合金掩膜微图形化Si(111)衬底上的周期为1mm1mm方块区域内生长出无裂纹GaN连续外延膜，，并通过在方块之间Al-Si掩膜区的硅衬底内产生裂纹，实现了应力释放，从而有效地解决了硅衬底GaN外延膜发生龟裂的难题。 3.通过引入阱后同温GaN cap层，成功地实现了对InGaN/GaN多量子阱绿光LED低温生长的阱层InGaN材料的保护作用。研究表明，cap层厚度在一定范围内增加，InGaN阱层的In组分升高且分布更均匀，InGaN材料质量和量子阱界面特性变好。具有25cap层的绿光器件的外量子效率(EQE)及EQE最高值对应的电流密度分别是15cap层器件的1.39倍和10倍，文中对此给出了相应解释。 4.经过工艺优化，研制的厚度为25cap层结构的硅衬底垂直结构绿光LED芯片，经封装在350mA直流驱动下(电流密度35A/cm2)，主波长为519nm，内量子效率40.3%，工作电压2.99V，光功率达235mW，这是目前报道的硅衬底绿光发光二极管最好水平。 5.通过引入500Torr高压条件下生长的p-GaN层，在具有大V型坑结构的InGaN/GaN蓝光LED外延结构中，成功地实现了对量子阱区V型坑的填平作用，芯片反向漏电下降，器件发光效率增大；通过工艺优化，研制的具有此结构外延片制造的垂直结构大功率蓝光LED芯片在350mA直流驱动下(电流密度35A/cm2)，主波长为450nm，内量子效率达79.5%，硅胶封装器件的工作电压为3.05V，光功率达595mW，与蓝宝石衬底蓝光LED市场产品的先进水平持平，从而有力地表明硅衬底LED是一条行之有效的半导体照明新技术路线。
[Abstract]:The solid-state lighting based on GaN based LED chip has high luminous efficiency, long life, fast response, near linear change of light intensity with current and pulse width. It can work in severe vibration and bad environment and does not contain environmental harmful substances. It has become the first choice for new generation of general lighting lamps and lanterns. The development of material growth and device manufacturing technology for GaN based light-emitting diodes has made considerable progress, and the efficiency and reliability of the device have been greatly improved, especially the successful implementation of GaN LED epitaxial technology and chip manufacturing technology on silicon substrate, the cost of the chip is further reduced, and the rapid replacement of incandescent lamps and fluorescent lamps by the LED lamp has been added. The process of using the lighting field.
In this context, a study on the growth of GaN based materials and devices on silicon substrate is carried out. First, the lateral epitaxial growth of GaN materials on Si (111) substrate of Al alloy mask is studied. Then, the quality and chip luminescence properties of the same temperature cap layer and cap layer thickness on the green InGaN/GaN MQWs LEDs quantum well materials are studied. The effect of the wet surface coarsening on the efficiency of the blue light LED chip is improved. Finally, the reliability of the high power GaN diode with the vertical structure of the silicon substrate is studied and analyzed.
1. the Al-Si alloy mask technology for the epitaxial growth of GaN material on silicon substrate is proposed. By evaporation of 150 metal Al on the surface of Si (111) substrate, the Al metal graph is made by photolithography. Then the alloy diffusion is carried out at high temperature 1200 C, and the graphical silicon substrate of the Al-Si alloy mask is obtained. The experiment shows that the growth of the Al-Si alloy mask will not grow. GaN, therefore, Al-Si alloy technology is an effective mask method for epitaxial growth of GaN materials on Si substrates.
2. by optimizing the strip mask parameters of Al-Si alloy and the growth conditions of GaN epitaxy, the crack free GaN continuous epitaxial film is successfully grown in the 1mm1mm block region on the Al-Si alloy mask micrographic Si (111) substrate, and the stress release is realized by producing a crack in the silicon substrate of the Al-Si mask region between the blocks. The problem of cracking of GaN epitaxial film on silicon substrate has been solved.
3. through the introduction of the well GaN cap layer after the well, the protection of the well layer InGaN material for the low temperature growth of the InGaN/GaN multi quantum well green LED is successfully realized. The study shows that the thickness of the cap layer is increased in a certain range, the In group of the InGaN well layer is higher and the distribution is more uniform, the quality of the InGaN material and the properties of the quantum well interface become better. The 25cap layer is of the 25cap layer. The external quantum efficiency (EQE) of the green device and the current density of the highest EQE value are 1.39 times and 10 times of that of the 15cap layer device, respectively.
4. through the process optimization, the silicon substrate vertical structure green light LED chip with the thickness of 25cap layer is developed. The chip is encapsulated in the 350mA DC drive (current density 35A/cm2), the main wavelength is 519nm, the internal quantum efficiency is 40.3%, the working voltage is 2.99V, and the light power is 235mW, which is the best level of the present silicon substrate green light emitting diode.
5. by introducing the p-GaN layer grown under the high pressure of 500Torr, in the InGaN/GaN blue LED epitaxial structure with a large V pit structure, the filling of V pits in the quantum well area is successfully realized, the reverse leakage of the chip and the luminous efficiency of the device are increased, and the vertical structure made of this structural epitaxial piece is developed through the process optimization. The high power blue light LED chip is driven by 350mA DC (current density 35A/cm2), the main wavelength is 450nm, the internal quantum efficiency is 79.5%, the working voltage of the silicon rubber package device is 3.05V, the light power is 595mW, and the advanced level of the blue light LED market product of the sapphire substrate is flat. Thus the silicon substrate LED is an effective semiconductor. Lighting new technical routes.
【学位授予单位】：南昌大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM923.34

【参考文献】