电场对含空位缺陷硅结构影响的第一性原理研究

First-principle study on effects of electric field on Si vacancy structures

用分子动力学模拟和第一性原理计算分析方法,研究电场对含空位缺陷硅结构的影响。分子动力学结果表明,硅(100)晶面处的空位数量,总体随着电场强度的增强而增加。当电场在8.90×10~6 V/cm和1.35×10~7 V/cm之间时,空位数达到最大饱和数值10,并保持稳定。第一性原理计算结果表明,能带结构中的缺陷能级等效于降低价带和导带之间的带隙值,导致空位结构中隧穿电流变大。此外,缺陷能级也会导致空位结构中的静态介电常数变大,从而引起电容-电压特性值变大。

By using molecular dynamic simulation method and first principle calculations method,the influence of electric field on silicon with vacancies were investigated.The molecular dynamics results demonstrate that the vacancy quantity in Si(100)surface increases along with the increase of electric field in general.The vacancy quantity reaches and keeps a maximum saturation value of10,when the electric field is between8.90×106V/cm and1.35×107V/cm.The first principle calculations reveal that the tunneling current is enhanced in vacancy structure.It is owing to that the gap value between valence band and conduction band is reduced by the defect levels in band structure.Besides,the static dielectric constant in vacancy structure gets lager,resulting in higher capacitor-voltage value.