Analysis Of The Preparation Technology Of High Quality Aluminum Nitride Crystal

Since the birth of semiconductor materials,the research on semiconductor devices has never stopped.Has now developed to the third-generation semiconductor,in order to support the implementation of the "Minamata Convention" on mercury,will restrict the production and use of products containing mercury.At present,it is urgent to study the replacement products of mercury source UV,so the third-generation semiconductor AlN enters the field of researchers’ vision and quickly becomes the hot material of ultraviolet equipment.In this paper,the existing AlN production technology and the difficulty of laser production are summarized.In combination with the tutor’s project and my own learning practice at the beginning of the study,I decided to study the growth of high quality AlN crystal substrate in laser production.And Growth of AlN crystals was calculated by simulation software.First,the initial process of the growth of AlN crystal PVT is calculated.The model needs to model on the surface of Al polarity AlN crystal(0 0 0 1)widely used in the present preparation,and discuss the diffusion of AlN steam over the surface and the surface combination during the PVT growth.Based on first principles calculation,to establish the AlN crystals(0 0 0 1)single vacancy defects on the surface of monatomic raised growth model,simulates the different convex atoms on the combination of different components of AlN steam and diffusion.The initial growth process of AlN crystal growth was found.Macroscopic AlN crystals were then discussed.During the growth process of AlN crystal,the growth process and the cooling process are the most important.Firstly,the crucible is modeled and reliable temperature field data are obtained.Secondly,the cooling of AlN crystal is simulated under the condition of the temperature field,and the internal temperature distribution of AlN crystal is obtained,which can obtain the temperature gradient in different regions of the crystal.After this,the method of reducing the temperature gradient was simulated.A multilayer crystal growth structure with SiC as a transition layer is gradually formed.To get the temperature field of the structure of AlN-SiC crystal growth simulation,from the overall temperature distribution and the centerline temperature distribution in the two aspects has carried on the simulation of the temperature gradient under the condition of different parameters,and on this basis to obtain the stress level within the crystal.This multi-layer crystal growth structure effectively solves the problem of the stress level of AlN crystals during the cooling process.Finally,in order to cope with the research in macroscopic AlN crystals,the existing PVT growth equipment structure was improved according to the Al N-SiC multilayer structure designed in the cooling process.In order to find a device capable of producing multiple layers of different materials in the process of PVT growth.By reading some literature,the growth of multilayer structure was realized by means of growth condition control.After the structural design of the new crucible is completed,the feasibility of SiC crystal as a buffer layer in the growth of AlN crystal is also discussed.Thus,the structure of multi-source PVT growth equipment was accomplished.