摘要
采用第一性原理赝势平面波方法对（111）应变下立方相Ca2P0.25Si0.75的能带结构及光学性质进行模拟计算，全面分析了应变对其能带结构、光学性质的影响。计算结果表明：在-8％～0％压应变范围内，随着应变的逐渐增大导带向低能方向移动，价带向高能方向移动，带隙逐渐减小，但始终为直接带隙；在O％～2％张应变范围内，随着应变的增加，带隙逐渐增大，应变为2％时直接带隙达到最大Eg=0．60441eV；当张应变为4％,Ca2P0.25Si0.75变为间接带隙半导体。Ca2P0.25Si0.75的介电常数和折射率随着张应变的增加而增加；施加-2％-0％压应变时，介电常数和折射率逐渐减小，到达一2％时达到最小值，此后随着压应变的增加介电常数和折射率逐渐增大。施加压应变时吸收谱和反射谱随着应变的增大而减小，施加张应变时吸收谱和反射谱随着应变的增大而增大。应变可以改变立方相Ca2P0.25Si0.75的电子结构和光学常数，是调节其光电传输性能的有效手段。
Energy band structure and optical properties of the cubic Ca2P0.25Si0.75 with strain on the （111） surface are calculated by the First Principle pseudo-potential method based on the density functional theory （DFT）, and the effect of strain on energy band structure and optical properties is analyzed. The results show that under the compressive strain range of -8%~0%, it is direct semiconductor but the band gap decreases with the increase of strain, the conduction band moves to low energy while the valence band moves to high energy; when the tensile strain is 0%--2%, the band gap increases with the increase of strain, when the tensile strain is 2%, the direct band gap is maximum, Eg=0.60441 eV; when the tensile strain is 4%, it turns to indirect semiconductor. The dielectric constant and the refractive index of cubic Ca2P0.25Si0.75 increase with the tensile strain; when the compressive strain is- 2%-0%, the dielectric function and the refractive index decrease; when the compressive strain reaches -2%, the dielectric function and the refractive index are minimum, then they increase with growth of the compressive strain. The absorption and reflectivity decrease with the increase of compressive strain, while they increase with the increase of tensile strain. The energy band structure and optical properties the cubic Ca2P0.25Si0.75 are influenced by strain, which is an effective means to adjust photoelectric transmission performance of cubic Ca2P0.25Si0.75.
出处
《激光与光电子学进展》
CSCD
北大核心
2014年第9期162-168,共7页
Laser & Optoelectronics Progress
基金
国家自然科学基金(51266002)
教育部科学技术研究重点项目(210200)
贵州省科学技术联合基金(LKM201130)
贵州省优秀科技教育人才省长专项资金(201174)
