Research On Light Absorption And Thermal Conductivity Of Two-dimensional Novel AlN Semiconductor

In two-dimensional materials,aluminum nitride(AlN)has an important application value in the development of electronic devices due to its excellent stability and thermal transport properties.However,the wide band gap of AlN seriously hinders its application potential.In order to further break through its performance bottleneck,we finds a novel porous vacancy AlN configuration by structural search method based on evolutionary algorithm.Due to its special porous configuration,C and Si atoms and carbon triangle ring(TC)can be introduced into the pore to form a novel twodimensional X-AlN(X=C,Si and TC)configuration,so as to improve its optical and thermal properties.In addition,the dynamic and thermal stability of porous vacancy AlN and X-AlN(X=C,Si,and TC)configuration constructed by introduced C and Si atoms and triangle carbon rings into the porous vacancy of AlN is verified by firstprinciples calculations.The specific reasons for the change of physical properties of XAlN configuration caused by the introduction of different atoms and the abnormal thermal transport of X-AlN caused by stress stretching were also revealed.Relevant calculation results are as follows:(1)After the introduction of X atom,due to the localization of C/Si-pz electrons,isolated band is generated near the Fermi surface of C-AlN and Si-AlN configuration,and their bandgap values decrease from 4.12 e V(AlN)to 0.65 and 1.85 e V,respectively,which significantly improves the wide band gap of AlN.The delocalized π bond is formed by the C-pz hybridization between the triangle carbon rings,which reduces the energy and realizes the indirect to direct band gap transition.Secondly,due to the existence of asymmetric Al-N bonds and vertically stacked N-N bonds around the vacancy,the porous vacancy surface AlN has the lowest thermal conductivity.The introduction of C and Si atoms reduces the anharmonicity of the structure,and the distortion of C atom is relatively small,so it has a high thermal conductivity.The triangle carbon in TC-AlN impedes phonon scattering between FA and the other phonon modes,and has the weakest anharmonic due to the strongest bond strength,made it the most anharmonic.(2)In view of the anomalous thermal transport phenomenon that the lattice thermal conductivity of X-AlN configuration increases first and then decreases under biaxial tension,we demonstrates that the reason for the occurrence of this anomalous phenomenon is the competition between the low anharmonicity brought about by the N-N bond which increases with the strain and the softening of phonon mode which decreases the group velocity from the group velocity and the group velocity.This work provides a new way to regulate the performance of two-dimensional AlN.It provides new insights for the design of promising new two-dimensional semiconductors,and provides powerful guidance for improving the electronic,optical and thermal properties of semiconductors.