宽禁带氧化镓高压肖特基器件的基础研究

The project aims at the high performance Ga2O3 Schottky diode,with the relationship between the defects and the device performance as the joint,on the basis of ozone assistance pulsed MOCVD to enhance the movement of the Ga atoms on the substrate surface,promote the 2D growth,suppress the formaiton of defects and to realize the fabrication of n type Ga2O3 film with less defects at low temperature,on the support of high oxygen pressure annealing to repaire the lattice defects and reduce the concentration of oxyge vacancy.we concerned on the physical mechnism of n-Ga2O3 growth at low temperature, the internal mechanism of high oxygen pressure annealing and the effects of dislocations and defects on device performance,carried out the experimental research on film growth and device fabrication to analyze the influence of the technology parameters on the material and device characteristics and theoretical research on first principle,molecular dynamics and thermal dymatics simulation to analyze the diffusion of Ga atoms and Si atoms on substrate surface,understand the formation and change of defects,know the formation energy of point defects and the transformation conditions among different energy states.Based on the microanalysis of defects effect on device performance,the optimization of the film and device technology and the improvement of device structure will be promoted and realize the Schottky diode with the conducton resistance less than 4.0m.Ohm.cm2 and the breakdown voltage greater than 2000V.

本课题以实现高性能氧化镓肖特基二极管为目标，以位错缺陷与器件性能相关性研究为纽带，以臭氧辅助MOCVD脉冲法增强低温下Ga原子在衬底表面迁移，促进Ga2O3二维生长，抑制位错缺陷形成，实现高质量n型Ga2O3薄膜的同质外延为基础，以高氧压退火修复晶格缺陷，降低氧空位浓度为辅助，围绕n型Ga2O3低温生长的物理机理，高氧压处理的内在机制和位错缺陷影响器件性能的作用方式等关键问题，开展材料生长和器件制备的实验研究，分析工艺参数对材料和器件性能的影响；开展第一性原理、分子动力学和热动力学的理论研究，分析镓原子和硅原子在衬底表面的扩散行为，了解位错缺陷的形成和变化，不同条件下点缺陷的形成能和缺陷能态发生转化的条件，基于位错缺陷影响器件性能的微观分析，推动材料、器件制备工艺的优化和器件结构的改进，最终实现导通电阻小于4.0毫欧姆平方厘米，击穿电压大于2000V的Ga2O3肖特基二极管。

本项目以实现高性能的氧化镓肖特基二极管为目标，通过采用MOCVD脉冲法增强Ga原子在衬底表面的横向迁移，促进Ga2O3二维生长，改善薄膜质量，采用氧气氛围下的后续热退火促进薄膜再结晶，降低氧空位缺陷浓度，进一步提高薄膜质量，在此基础上，采用剥离方式研制的带有场板结构的水平β-Ga2O3肖特基二极管，其正向导通电阻约为24.3mΩ•cm2，反向击穿电压大于3000V，直流功率FOM为500MW/cm2，创同期历史新高；采用Bevel结构结合原位F等离子体处理技术研制的垂直型β-Ga2O3肖特基二极管，正向导通电阻仅为2.5 mΩ•cm2，反向击穿电压达到1050V；选用与Ga2O3导带底能带差仅为~0.3eV高介电常数TiO2作为介质层研制的金属/TiO2/β-Ga2O3 MDS,正向导通电阻为3.3 mΩ•cm2,反向击穿电压为1010V，后两项研究成果达到同期国际水平。最后通过对β-Ga2O3肖特基二极管的电应力测试证实该器件未出现电流崩塌现象，在未来高压开关应用中具有巨大的前景。