Electronic Structure And Thermoelectric Properties Of GaN Low Dimensional Materials

In the thermoelectric industry,common consumables such as Bi2Te3 contain toxic substances,and the production process will damage human body.Moreover,the working temperature is about 800 K,the output efficiency is low at high temperature,and there is no good high temperature stability.At present,there is an urgent need for the emergence of non-toxic,non-polluting and high-temperature stable alternative materials.Gallium nitride(GaN),as a nitride semiconductor,is non-toxic,pollution-free and has good thermal stability.GaN is a potential thermoelectric material.But the thermoelectric merit value of GaN bulk material itself is low,so it needs to be treated in order to improve the thermoelectric merit value and meet the material requirements of industrial experiments.Based on the first principle of density functional theory and Boltzmann theory,GaN bulk materials were treated in low dimension,and armchair nanotubes with chirality of(5,5)and surface structures in(001)direction were designed.The Ga defect and N defect models are established.The theoretical calculations of electronic structure and thermoelectric properties are carried out on VASP and BoltzTraP.The data files containing the core parameters such as band structure,Sebeck coefficient and carrier concentration are obtained.The theoretical data are imported into data processing software for comparison and analysis.It was found that the thermoelectric extremum of N-type GaN nanotubes was 1.9 at 1100 K,while the bulk material was only 0.019.Low dimensionality increases the thermoelectric merit value of GaN to 100 times,while the extreme value of Ga defect structure of GaN nanotubes is 2.8,and the treatment of point defects increases by 47.37% on the basis of nanotubes.At different temperatures,the thermoelectric merit value of GaN low-dimensional materials is always greater than that of GaN bulk materials,and the thermoelectric merit value increases with the increase of temperature,which has good high temperature stability.Theoretical analysis shows that GaN low-dimensional materials can effectively improve the thermoelectric merit value,and also provide a good theoretical basis for the experimental study of industrial production of alternative consumables.