First-principles Study Of AlN Containing Carbon Impurity

Aluminum nitride(AlN)is a typical representative of the third generation of semiconductor materials.Due to its excellent electrical and optical properties,the application of AlN materials has also become very widespread.However,the preparation of large-size,high-quality AlN bulk single crystal materials is still a big challenge.Although there have been many studies on the doping of AlN,efficient,stable,and controllable doping is still a problem at the present stage.All these have hindered the development of new AlN-based devices,there are two reasons for this situation.First,the current stage of research is mainly based on software simulation,the ideal situation is considered.Although there are many uncontrollable factors in the actual preparation process of AlN materials,there will be some errors with experimental data.However,with these simulation data as a basis for research,a large amount of manpower and material resources can be saved.Therefore,They are still of great reference value.In the simulation experiments,an AlN supercell model of 32 atoms or 72 atoms is generally selected as the research object in the experiment.In the case of single doping or co-doping,one Al atom or N atom is replaced with the corresponding impurity atom.The doping concentration of the doping method is higher than that of the actual doping.If a larger supercell model is selected,a larger calculation cost will be required.Second,it is the problem of impurity atoms in the preparation of AlN.At present,physical vapor transport(PVT)method is one of the most effective ways to prepare high-quality,large-size AlN crystals,and it is also a method that uses more,but there are some impurities that cannot be completely eliminated during the preparation process,such as C,O etc.The presence of these impurities will affect some of the characteristics of AlN,However,if we can analyze and use these impurities and turn the seemingly unfavorable factors into favorable factors,we will greatly improve the production efficiency of AlN,and we will be able to exert its practicality.Respect to oxygen atoms,a large number of studies have shown that oxygen atoms can be co-doped with elements such as alkali metal elements to achieve p-type doping of AlN.Respect to carbon atoms,C-Si co-doping is also used to achieve p-type doping of AlN.There have to be aware of is that the donor impurities doped with the acceptor impurities are difficult to remove from the crystal after the completion of the growth,which will greatly affect the actual doping.Efficiency,and when using SiC as a substrate for growing AlN crystals,doping with C,Si can overcome this problem.While carbon atoms is a group of IV element,its application in AlN is also more flexible.For example,replacing one Al atom with a C atom is an n-type doping,and replacing an N atom with a C atom is a p-type doping,and the C atoms is also an impurity atoms.Therefore,some characteristics of AlN doping with C atoms deserve our in-depth study.In this paper,the doping of C atoms is taken as the main line,and the pure AlN is used as the auxiliary line to study and compare.The simulation tool used is the CASTEP module of Material Studio software.The properties of the research object are reflected by the density of electron states,energy band structure,and optical properties.The research contents include the transition states of AlN containing C impurities,the replacement of complete AlN cells after the completion of the growth,the gap doping,and the co-doping of different positions of the Group II and C atoms.Analyzing the doping of C atoms from different aspects will bring new inspiration and theoretical support for AlN doping research.