不同支撑载体对GaN基LED薄膜应力及发光性能的影响

发布时间：2018-06-20 16:53

本文选题：硅衬底 + GaN　；参考：《南昌大学》2015年硕士论文

【摘要】：GaN基LED在照明领域获得了广泛应用,已经与人们的生活息息相关,但现有生产工艺的改进、新技术的开发、相关物理机理的研究仍然是整个领域的热点。目前,商品化的GaN基LED按外延衬底划分共有碳化硅(SiC)、蓝宝石(Al2O3)及硅(Si)衬底三条技术路线。尽管硅衬底GaN基LED在中国率先实现了产业化,并成为半导体照明的主要三条技术路线之一,然而它还有大量的科学技术问题没有解决,值得多学科交叉融合进行深入研究。GaN基LED外延生长、芯片制造、器件封装、和使用过程中各种应力对器件光电性能影响的研究是当前研究热点,文献中对此现象的研究主要集中在GaN没有从外延衬底剥离的同侧结构器件,对垂直结构GaN基LED器件尤其是硅衬底GaN基LED器件中各种应力的研究还处于初始阶段。基于硅衬底GaN基LED平台,本文设计和制备多种具有不同应力状态的垂直结构GaN基LED以及不同应力状态的LED薄膜,研究其应力与LED光电性能之间的关系,以及通过高分辨率X射线衍射仪(HRXRD)测试分析了不同应力状态下LED薄膜内在应力的情况以及量子阱的情况。获得了一下研究成果:1)将硅(Si)衬底上外延生长的氮化镓(GaN)基发光二极管(LED)薄膜转移至含有柔性粘结层的基板上,获得了不受衬底和支撑基板束缚的LED薄膜。利用高分辨率X射线衍射仪(HRXRD)研究了薄膜转移前后的应力变化,同时对其光致发光(PL)光谱的特性进行了研究。结果表明:硅衬底GaN基LED薄膜转移至柔性基板后,GaN受到的应力会由转移前巨大的张应力变为转移后微小的压应力,InGaN/GaN量子阱受到的压应力则增大;尽管LED薄膜室温无损转移至柔性基板其In GaN阱层的In组分不会改变,然而按照HRXRD倒易空间图谱通用计算方法会得出平均铟组发生了变化;GaN基LED薄膜从外延片转移至柔性基板时其PL谱会发生明显红移。2)将硅(Si)衬底上外延生长的氮化镓(GaN)基发光二极管(LED)薄膜剥离转移到新的硅基板和紫铜基板上,并获得了垂直结构的LED芯片,对其变温变电流电致发光(EL)特性进行了研究。结果表明:当环境温度不变时,在13K低温状态下铜基板芯片的EL波长始终大于硅基板芯片约6nm,在300K状态下随着驱动电流的加大铜基板芯片的EL波长会由大于硅基板芯片3nm左右而逐渐变为与硅基板芯片重合;当驱动电流不变时,环境温度由13K升高到320K,两种基板芯片的EL峰值波长随温度升高呈现S型变化并且波谱逐渐趋于重合;在100K以下温度时铜基板芯片的Droop效应比硅基板芯片明显,在100K以上温度时硅基板芯片的Droop效应比铜基板芯片明显。可能是由于两种芯片的基板具有不同的热膨胀系数和热导率导致了其变温变电流的EL特性不同。
[Abstract]:GaN-based LED has been widely used in the field of lighting and has been closely related to people's lives. However, the improvement of existing production technology, the development of new technology and the research of related physical mechanism are still the focus of the whole field. At present, commercial GaN-based LEDs are divided into three technical routes according to epitaxial substrates: silicon carbide (sic), sapphire (Al _ 2O _ 3) and Si _ 2O _ (3) substrates. Although GaN-based LED on silicon substrate is the first to realize industrialization in China and become one of the three main technology routes of semiconductor lighting, it still has a large number of scientific and technological problems that remain unsolved. The research on the effects of various stresses on the optoelectronic performance of gan based LED, such as epitaxial growth, chip fabrication, device packaging, and the process of application, is a hot research topic at present. The research on this phenomenon is mainly focused on the ipsilateral structure devices which gan is not stripped from the epitaxial substrate. The study of the stress in the vertical structure GaN-based LED devices, especially in the Si substrate GaN-based LED devices, is still in the initial stage. Based on gan based LED platform on silicon substrate, several kinds of vertical gan based LEDs with different stress states and LED thin films with different stress states are designed and fabricated in this paper. The relationship between the stress and the photoelectric properties of LEDs is studied. The inner stress and quantum well of LED thin film under different stress states were analyzed by high resolution X-ray diffractometer (HRXRD). In this paper, we obtain the research result: 1) transfer the epitaxially grown Gallium nitride (GaN-based) LED) thin films on Si Si) substrates to the substrates containing flexible bonding layers, and obtain the LED thin films which are not bound by the substrate and the supporting substrates. High resolution X-ray diffraction (HRXRD) was used to study the stress changes of the films before and after transfer. The photoluminescence (PL) spectra of the films were also studied. The results show that the stress of gan is changed from the large tensile stress before transfer to the compressive stress of InGaN / gan quantum well after the transfer of GaN-based LED thin film on silicon substrate to the flexible substrate, while the compressive stress of InGaN / gan quantum well increases. Even though LED films are transferred to flexible substrates at room temperature without loss, the in component of the in gan trap layer will not change. However, according to the general calculation method of HRXRD reciprocal spatial pattern, it can be concluded that the average indium group changes when the PL spectra of GaN-based LED films transfer from the epitaxial wafer to the flexible substrate, the PL spectra of the films will be red-shifted significantly. 2) the nitridation of epitaxial growth on Si / Si) substrates will occur. Gallium-doped gan (GaN-based) LED) thin films are peeled onto new silicon and copper substrates. A vertical LED chip is obtained, and the ELL characteristics of the LED chip with variable temperature and current are studied. The results show that when the ambient temperature is constant, At low temperature of 13K, the El wavelength of copper substrate chip is always larger than that of silicon substrate chip about 6 nm. At 300K state, the El wavelength of copper substrate chip will change from about 3nm larger than silicon substrate chip to superposition with silicon substrate chip with the increase of driving current. When the driving current is invariant, the ambient temperature increases from 13K to 320K, and the El peak wavelength of the two kinds of substrates varies with the increase of temperature, and the spectra of the two kinds of substrates tend to coincide with each other. The droop effect of copper substrate chip is more obvious than that of silicon substrate chip at temperature below 100K, and the Droop effect of silicon substrate chip is more obvious than that of copper substrate chip at temperature above 100K. It may be that the different thermal expansion coefficient and thermal conductivity of the two kinds of substrates lead to the different El characteristics of the substrates with variable temperature and current.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8;TB383.2

【参考文献】