Research On RMF-THM GaInSb Crystal Growth Process

As a typical Ⅲ-Ⅴcompound semiconductor material,GaInSb can be widely used in the field of detectors,lasers,optoelectronic communications,integrated circuits and satellite navigation due to its high electron mobility and narrow band gap.However,the quality of GaInSb crystal had not been significantly improved due to the large segregation tendency of In element and the immature preparation process causes many defects such as dislocation density in the crystal.In this paper,a rotating magnetic field was applied to the experimental process of growing GaInSb crystal by the Travelling Heater Method（THM）.The forced convection introduced by the rotating magnetic field was used to enhance the convection,heat transfer and mass transfer of the melt,so as to increase the uniformities of temperature distribution and stress distribution at the solid-liquid interface.The uniformity of the solute distribution further improved the shape of the solid-liquid interface and reduced defects such as component segregation and dislocation density in the crystal.The effect of the frequency and intensity of the rotating magnetic field on the quality and performance of GaInSb crystal were investigated.X-ray diffraction（XRD）,energy dispersive spectrometer（EDS）,metallographic microscope,Hall effect tester,and Fourier transform infrared spectrometer were applied to test and characterize the crystal.The best growth conditions and parameters were finally obtained.This paper mainly drew the following conclusions:（1）In this experiment,a rotating magnetic field（RMF）was applied to grow GaInSb crystals using a Travelling Heater Method（THM）,high-quality Ga_0.86In_0.14Sb crystal（φ25mm×100mm）were prepared with a home-made RMF-THM crystal growth furnace.（2）The rotating magnetic field significantly improved the microstructure and properties of GaInSb crystal and improved the crystal quality.After the application of rotating magnetic field,the surface roughness and the crystallinity of the crystal increased;the shape of the solid-liquid interface stabilized,the segregation of the In component was significantly reduced.The defects such as impurities,dislocation density and twins of the crystal were reduced;The carrier mobility increased and the infrared transmittance also increased.（3）The effect of rotating magnetic field intensity on the microstructure and properties of the GaInSb crystal were investigated.The conclusions were as follows:As the intensity of rotating magnetic field increased,the crystallinity of the crystal increased.When the intensity of rotating magnetic field was 25 m T,the 2θof the GaInSb crystal decreased by 0.191°and the FWHM decreased to 96″.The segregation of the In element in the crystal reduced,the radial segregation of the In component was reduced to 0.031 mol%/mm and the axial segregation was reduced to 0.038 mol%/mm.The dislocation density of GaInSb crystals decreased to 5.295×10³ cm^-2.The inherent defects and structural defects in the crystals were significantly reduced.The electrical properties of the crystal were improved,the carrier mobility was increased to 1.902×10³cm²（V s）,and the resistivity was decreased to 1.047×10^-3Ω·cm.The infrared transmittance of the crystal was increased to 39%.（4）The effect of rotating magnetic field frequency on the microstructure and properties of the GaInSb crystal were investigated.The conclusions were as follows:As the frequency of rotating magnetic field increased,the crystallinity of the crystal increased.When the frequency of rotating magnetic field was 50 Hz,the 2θof the GaInSb crystal decreased by 0.157°,and the FWHM decreased to 117″.The segregation of the In element in the crystal was reduced,in which the radial segregation of the In component was reduced to 0.086 mol%/mm and the axial segregation was reduced to0.04 mol%/mm.The dislocation density of crystal was reduced to 7.274×10³ cm^-2,and defects such as impurities,twins,and microcracks in the crystal were significantly reduced.The electrical properties of GaInSb crystals were improved,the carrier mobility was increased to 1.709×10³ cm²（V s）,and the resistivity was reduced to1.377×10^-3Ω·cm.When the frequency of rotating magnetic field was 50 Hz,the infrared transmittance of the crystal was reached 38%.