外压调制对Cr-Se共掺杂单层MoS2光电特性的影响

Effect of Strain on the Photoelectric Properties of Cr-Se Co-doped Monolayer MoS2

采用基于第一性原理的贋势平面波方法,对比研究了Cr-Se共掺杂单层MoS2未施应变和(0001)面施加应变的光电特性。计算结果表明:未施加应变体系属直接带隙半导体,张应变下体系的带隙值随应变增加而减小,压应变下带隙值随应变增加先增加后减小,在应变为-6%时转化为Γ-M间接带隙半导体,带隙值达到极大值1.595eV;介电函数和折射率随张应变的增加而增加,随压应变增加先减小后增大,在压应变为-6%时达到极小值3.627和1.905;光电导率和能量损失函数随张应变增加而减小,随压应变增加先增加后减小,应变分别为-5%和-2%时达到极大值2.588和9.428。可见,应变能更精细地调制Cr-Se共掺杂单层MoS2的光电特性。

The effect of（0001）surface strain on the electronic structures and optical properties of Cr-Se co-doped monolayer MoS2 was studied by the first-principle pseudo-potential method based on density functional theory（DFT）.The results show that Cr-Se co-doped monolayer MoS2 is a direct semiconductor,and its band gap value decreases with the tensile strain increasing,but increases firstly and then decreases with the compressive strain increasing.It can transform into aΓ-M indirect semiconductor with Egmax=1.595 eV at the-6% compressive strain.The dielectric function and refractive index increase with tensile increasing,but they decrease firstly and then increase with the compressive increasing and their minimum values are respectively 3.627 and 1.905 at the-6% compressive strain.The conductivity and loss function decrease with tensile increasing but they increase firstly and then decrease with the compressive increasing,and the maximum value of conductivity is 2.588 at the-5% compressive strain,while the maximum value of loss function is 9.428 at the-2%compressive strain.Obviously,the photoelectric properties of Cr-Se co-doped monolayer MoS2 have been expertly modulated by straining.