Experimental Recording And Analysis System For AIN Crystal Growth

Optoelectronic information technology has developed rapidly based on semiconductors.AlN(aluminum nitride)is a typical representative of the third generation of semiconductors,which has excellent optical,acoustic,electrical and mechanical properties,such as wide band gap(6.2 eV),high breakdown field strength,high thermal conductivity,high temperature resistance and chemical resistance.Therefore,it has a very broad application prospect in the fields of preparing radiation-resistant,high-frequency and high-power devices.The preparation of large-size,high-quality AlN crystals is an important research topic,and research shows that preparing AlN single crystals by PVT(Physical Vapor Transport)is one of the most effective methods.Although the preparation of AlN crystal by PVT has made great progress after several decades of research,large-size and high quality AlN single crystals have not been obtained for commercial production.During the research,optimizing the process is mainly relied on theoretical analysis and data comparison.At present,most research groups still use manual or semi-automatic method for crystal growth control.Due to the long experimental period and large amount of data,the above methods are difficult to achieve real-time data recording and data analysis,which are important for process optimization.In order to solve the problems,this paper optimizes the process of AlN crystals growth and studies the targeted experimental recording and analysis system.The research can be summarized as followed:(1)Optimize the process parameters and study the effects of different process parameters on the growth of AlN crystals.Studies have shown that the main process parameters of AlN single crystal growth include temperature gradient,nitrogen pressure,growth temperature and supersaturation pressure.The research group has designed a special equipment for crystal growth,which consists of a three-zone heating device,a vacuum device,a shielding gas device,temperature detectors,pressure detectors and a circulating water system.The control of process parameters is achieved by operating each device.In this paper,the growthconditions of different forms(whiskers,crystal needles and bulk crystals)of AlN crystals were compared,and the crystals were characterized by optical microscopy,scanning electron microscopy,Raman spectroscopy and X-ray diffractometry.(2)Established an effective experimental recording and analysis system.Based on the characteristics of crystal growth and the existing equipment,this paper designed an experimental recording and analysis system for AlN crystal growth.The system achieves automatic data recording,experimental classification,real-time data comparison,and remote control.The specific research includes realizing automatic recording of infrared temperature,furnace pressure and heater power,building data relationship model and data scheduling framework,achieving data retrieval and comparison,deploying control system and realizing signal transmission.In this paper,the influence of process parameters for AlN crystals growth was analyzed,and an experimental recording and analysis system was designed.The system not only realizes real-time recording data,but also conducts experimental classification and result statistics according to the process characteristics of preparing AlN crystals.By the help of the system,researchers can intuitively understand the impact of different process parameters on the experimental results,and make adjustments which would shorten the research cycle.In addition,the system realizes real-time monitoring of the growth process,which not only saves labor costs,reduces safety hazards,but also provides an application basis for industrial preparation of AlN crystals in the future.