PVT法掺锗碳化硅单晶制备、结构及性能研究

Silicon carbide (SiC) is a preferred material for high temperature, high-frequency, high-power semiconductor devices, owing to its superior properties, such as wide bandgap, high thermal conductivity, and high saturation velocity. Due to its adjustable lattice parameter, lower mismatch to epitaxial layer, modulatory the electronic band structure , lower contact resistance, and controllable polytype and point defects, germanium-doped SiC single crystal has promising research value and applied foreground in the area of semiconductor lighting, power electronics, photonic devices and band-gap engineering. This project intends to innovatively apply the physical vapor transport (PVT) method to grow SiC:Ge crystals. There are two key scientific problems: 1. Study the thermodynamics and dynamics mechanism of SiC:Ge crystal growth; 2. Regulate the electronic band structure, conduct research on theoretical knowledge of SiC:Ge, crystal growth and structure properties characterization. By exploring the techniques of germanium doping, defects control, stress suppression, regulation of physical properties, this project is dedicated to growing high quality single crystals, completing the device application and achieving new breakthrough in new method, new crystal and new application. The successful implementation of this project will innovate research on wide bandgap SiC crystals, enrich the functional materials discipline, fill the domestic blank, and has significant application value.

碳化硅（SiC）单晶具有宽带隙、高热导率、高饱和电子漂移速率等优点，已成为高温、高频、大功率半导体器件的优选材料。但掺锗碳化硅单晶材料具有可调节晶格参数，减少与外延层失配度，调节能带，减小接触电阻，控制晶型及点缺陷等优点，在半导体照明、电力电子器件、光子器件和能带工程领域具有重要研究价值和应用前景。本项目拟创新性地采用物理气相传输（PVT）法在碳化硅源粉中掺入锗元素生长碳化硅单晶。本项目拟围绕两个关键科学问题：1. 掺锗碳化硅单晶生长热力学和动力学机制；2. 掺锗碳化硅单晶能带调控机制，开展掺锗碳化硅晶体理论研究、材料生长和结构性能测试三项工作。探索锗元素掺杂技术、缺陷控制技术、应力抑制技术、物理性能调控技术，力求生长出高质量单晶，并能进行器件应用，实现新方法、新晶体、新应用的突破。本项目的成功实施将实现宽禁带SiC功能晶体的创新研究，丰富功能材料学科，填补国内空白，具有重大应用价值。

SiC作为第三代半导体材料，具有禁带宽度大、热导率高、击穿电场强度大、载流子饱和迁移速度高等优点，在半导体照明、航空航天、电力电子、微波通讯等高温电子以及高频大功率器件的领域，具有广阔应用前景。目前SiC单晶的研究工作的重心主要在n型和半绝缘类型上，较少关注IV族元素的掺杂。经过研究发现，掺杂Ge会影响SiC晶体结构，使晶格参数和能带结构发生改变，Ge元素可以降低SiC器件的接触电阻，提高其迁移率。因此，通过调整Ge元素的掺杂量，可以提高SiC器件的性能。目前，国内尚未有PVT法生长Ge掺杂SiC单晶的研究。本项目利用PVT法生长出Ge掺杂SiC单晶，并加工得到“开盒即用”的衬底片。其Ge掺杂浓度可达到1.19×1019/cm3，具有优良的电学性质，为提高SiC器件的性能奠定坚实的材料基础。本项目掌握了Ge掺杂SiC单晶的生长方法，理清了Ge掺杂对SiC的结构性能及晶体质量的影响，生长出高质量Ge掺杂SiC晶体，技术指标为微管密度2个/cm2，摇摆曲线半峰宽29弧秒，Ge掺杂浓度1.19×1019/cm3。