The modulation of the electronic properties of MoSi2N4/CdS heterostructure by interlayer spacing, strain, and electric field: A first-principles investigations

Abstract

In this work, the variation in the electronic properties of the MoSi₂N₄/CdS heterostructure with interlayer spacing, strain, and external electric field are investigated using first-principles methods. The MoSi₂N₄/CdS heterostructure is an indirect bandgap semiconductor with a band gap of 1.31 eV, work function of 5.45 eV, and Type II band edge alignment. As the interlayer spacing decreases, when D_Z-D (the difference between the actual interlayer spacing D_Z and the equilibrium spacing D = 3.2 Å) is -0.5 Å, the band gap increases to a maximum value of 1.55 eV. Then, the band gap gradually decreases to 0 eV at D_Z-D = -1.5 Å. When the compressive strain increases, the band gap increases to a maximum value of 1.93 eV at a stress of -4%, then gradually decreases to 1.28 eV. When an external electric field is applied, the band gap decreases to 0.68 eV with an increased positive electric field (MoSi₂N₄ layer pointing perpendicularly to the CdS layer). However, with a negative electric field, the band gap increases to the maximum value of 1.7 eV at the electric field strength of -0.3 V/Å, gradually decreasing to 0 eV. Based on the electron density difference, the density of state, projected band structure, mechanisms of band gap changes, and band edge alignment variations are analyzed. This paper found that by adjusting the interlayer spacing, applying planar biaxial strain, and applying external electric fields, the band gap and heterostructure type of the MoSi₂N₄/CdS heterostructure can be effectively tuned, providing theoretical references and new options for applications such as flexible electronic devices and wearable technology.