拉伸应变下SiC/SiO_(2)近界面碳缺陷的结构和电学特性演变  

Effect of Tensile Strain on the Structure and Electronic Properties of Carbon Related Defects Near the SiC/SiO_(2)Interface

作　　者：马玉洁 刘涵 张圆 崔鹏飞 苏艳 王德君 MA Yujie;LIU Han;ZHANG Yuan;CUI Pengfei;SU Yan;WANG Dejun(School of Control Science and Engineering,Dalian University of Technology,Dalian,Liaoning,116024,CHN;School of Physics,Dalian University of Technology,Dalian,Liaoning,116024,CHN)

机构地区：[1]大连理工大学控制科学与工程学院,辽宁大连116024 [2]大连理工大学物理学院,辽宁大连116024

出　　处：《固体电子学研究与进展》2024年第3期206-212,共7页Research & Progress of SSE

摘　　要：SiC/SiO_(2)界面拉伸应变对SiC MOSFET器件的电学性质和可靠性变化有重要影响。通过第一性原理密度泛函计算,建立了4H-SiC/SiO_(2)的界面结构,研究了不同拉伸应变对近界面碳碳双键(C=C)和碳氧双键(C=O)缺陷的结构和电子特性的影响。计算结果表明,在较小应变下C=C和C=O缺陷模型所受应力随应变线性增加,缺陷形成能减小,说明此时拉伸应变使这两种缺陷更容易形成。应变超过20%后,两种缺陷结构附近出现电子离域化,部分化学键断裂,缺陷结构遭到破坏。根据电荷态密度计算得出,拉伸应变的增加会使界面结构的带隙减小及缺陷能级位置改变,从而引起阈值电压漂移,这是拉伸应变引起SiC MOSFET性能不稳定的主要原因。The tensile strain at the SiC/SiO_(2)interface has an important impact on the electrical properties and reliability changes of SiC MOSFET devices.Through first-principles density functional calculations,this paper established the interface structure of 4H-SiC/SiO_(2)and studied the effects of different tensile strains on the structure and electronic properties of near-interface carbon-carbon dou⁃ble bond(C=C)and carbon-oxygen double bond(C=O)defects.The calculation results show that under smaller strains,the stress on the C=C and C=O defect models increases linearly with strain,and the defect formation energy decreases,indicating that tensile strain makes these two defects easier to form at this time.After the strain exceeds 20%,electron delocalization occurs near the two defect structures,some chemical bonds are broken,and the defect structures are destroyed.According to the charge state density calculation,the increase in tensile strain will reduce the band gap of the interface structure and change the defect energy level position,thereby causing a threshold voltage drift.This is the main reason why tensile strain causes unstable performance of SiC MOSFET.

关 键 词：碳化硅 近界面缺陷 拉伸应变 态密度 第一性原理 

分 类 号：TN386.1[电子电信—物理电子学]