Study On Convection And Heat Transfer During The Growth Of InP Crystals By Vertical Temperature Gradient Method

As a typical ?-? compound semiconductor,InP has the advantages of wide band gap,fast electron mobility and high photoelectric conversion efficiency.InP is an important semiconductor material for making various high frequency devices,optoelectronic devices and microelectronic devices.Understanding the process of heat transfer and liquid flow in crystal growth is of great significance for optimizing the process parameters and improving the quality of InP single crystal.In this paper,the temperature field and flow field of InP single crystal grown with VGF method were studied by numerical simulation,and also investigated the effect of rotating magnetic field on the liquid phase convection.The main contents and conclusions are as follows:(1)The distribution of temperature field and flow field in the melting zone during the growth of 3,4 and 6 inch InP single crystals was investigated.The results show that:In the three experiments,the temperature distribution in the melting zone was uniform,the isotherm density was small,and the solid-liquid interface always kept a relatively flat shape,which was beneficial to the growth of InP single crystal.Because the seed size and shoulder angle were constant,so the large crystal diameter would increase the shoulder area size.In the large-scale shoulder area,the flow pattern of the flow field changed from a single natural convection cell to two natural convection cells with the same flow direction.In the three experiments,the radial and axial velocity distribution in the melting zone was nonuniform,with the increase of crystal diameter,the nonuniformity of velocity distribution increased gradually.(2)In order to investigate the influence of external heater temperature on the temperature field and flow field distribution in the melting zone,three simulation experiments were carried out.The results show that: When the temperature difference of the six independent heaters increased,the isotherm density in the melting zone would increase,which lead to the increase of the axial temperature gradient.In the seed stage,the maximum axial temperature gradient was kept at the front of the solid-liquid interface,and the numerical value is stable.In the shoulder stage and the equal diameter stage,the crystal growth was carried out under a specific axial temperature gradient curve,and the axial temperature gradient distribution did not change with time.In the three experiments,the flow pattern of the flow field was the same,which indicated that there was no relation between axial temperature gradient and flow pattern.With the increase of the axial temperature gradient,the maximum flow velocity in the melting zone increased.(3)The effect of rotating magnetic field on the flow field distribution of InP single crystal grown with VGF method was investigated.The results show that: In the weak rotating magnetic field,the intensity and the maximum velocity of the flow field were obviously improved,but the distribution of the flow field in the melting zone had no obvious change,the natural convection was dominant in the flow field.In the strong rotating magnetic field,the strength of the flow field was further improved,and the flow pattern of the flow field changed,the secondary flow appeared in the melting zone.However,when the magnetic field intensity further increased,Taylor vortex would appear in the melting zone,and the distribution of flow field became unstable and changed with time.At this time,the forced convection induced by magnetic field is dominant and the natural convection was suppressed.