高纯4H-SiC单晶本征深能级点缺陷性质及形成机制研究

Solid-state microwave devices fabricated based on high purity semi-insulating 4H-SiC single crystal substrate, whose performance is much better than that of Si or GaAs devices, appear quite promising in the application of military radar communication. Due to the shortage of systematic and in-depth research on intrinsic deep level point defects，high purity semi-insulating 4H-SiC makes little progress, which impedes to a great development of microwave devices, therefore, this project is fairly meaningful strategically.The project is intended to investigate rules on SiC growth parameters which influence the formation of point defects, analyzing the relationship between species, concentration and energy levels of intrinsic deep level point defects with high temperature rapid annealing and high energy particle radiation, and study the effects of heat treatment on thermal stability of deep level point defects, to explore the formation，evolvement and compensation mechanism of deep level point defects in detail. With the help of the research mentioned above, the effective ways to control concentration of deep level point defects will be obtained in the conclusion of this project, in order to theoretically pave the way for the growth of high purity semi-insulating 4H-SiC. Finally, the growth of high purity semi-insulating 4H-SiC single crystal can be realized.

基于高纯半绝缘4H-SiC单晶衬底制备的固态微波器件的性能指标远远高于Si或GaAs器件，在军用雷达通讯领域应用前景巨大。目前由于缺乏对高纯4H-SiC单晶本征深能级点缺陷系统深入的研究，导致国内高纯半绝缘4H-SiC单晶进展缓慢，严重制约了我国微波器件的发展，因此该项目研究具有重大的战略意义。本项目拟对高纯4H-SiC单晶生长参数影响点缺陷形成的规律进行研究，分析高温快速退火，高能粒子辐照与本征深能级点缺陷种类、浓度以及能级之间的关系，研究热处理对深能级点缺陷热稳定性的影响，深入探讨深能级点缺陷形成、演变及补偿机制，获得控制深能级点缺陷浓度的有效途径，为高纯半绝缘4H-SiC单晶生长提供理论指导，并最终生长出高纯半绝缘4H-SiC单晶。

基于高纯半绝缘4H-SiC单晶衬底制备的固态微波器件的性能指标远远高于Si或GaAs器件，在军用雷达通讯领域应用前景巨大。目前由于缺乏对高纯4H-SiC单晶本征深能级点缺陷系统深入的研究，导致国内高纯半绝缘4H-SiC单晶进展缓慢，严重制约了我国微波器件的发展，因此该项目研究具有重大的战略意义。.本项目对高纯4H-SiC单晶生长参数影响点缺陷形成的规律进行研究，开展了高温退火及电子辐照工艺试验，分析了高温快速退火，高能粒子辐照与本征深能级点缺陷种类、浓度以及能级之间的关系，研究热处理对深能级点缺陷热稳定性的影响。采用碳硅直接反应并在生长过程中通氢气的方法来合成单晶生长用高纯SiC粉料，对合成粉料的物象、晶型、粒度和纯度等进行了表征。开展了氢气对高纯粉料合成的影响，研究了合成温度对粒度、产率、纯度的影响。研究了氢气辅助环境下生长参数对高纯半绝缘碳化硅单晶生长的影响。通过对晶片加工技术的研究，建立了金刚石多线切割SiC晶体的材料去除率模型，得出材料去除率对晶片翘曲度的影响。基于上述研究工作，最终生长出4英寸高纯半绝缘4H-SiC单晶。高纯粉料纯度>99.9999%，高纯半绝缘4H-SiC晶体尺寸4英寸，微管密度小于<1/cm2,电阻率>1010Ω•cm，晶片表面粗糙度<01nm。满足GaN外延材料生长的要求，保障了我国军用固态微波功率器件研发的自主可控。