The Preparation Of Nonstoichiometry Inp Crystal And The Study Of Related Defects

In recent years,with the development of high-speed optoelectronic IC and electronic devices,InP materials have attracted more and more attentions.However,the stoichiometry of InP melt has a great influence on crystal quality and optical properties of InP crystal.We combined crystal growth simulation with the pulling process,and pulling InP single crystal from indium riched and phosphorus riched melt respectively,the indium inclusions which were found in the crystal grown from indium riched melt and the pores which were found in the crystal grown from phosphorus riched melt were well studied.Using metallurgical microscope and scanning electron microscope to observe the morphology of indium inclusions and pores;using Huber method and metallographic microscope to study the dislocation around indium inclusions and pores;using Hall measurement to study the electrical properties of InP wafer;using photoluminescence spectra(PL)to study the optical properties of un-doped InP wafers which were grown from indium riched melt;and the crystal quality around inclusion and pores were characterized by X-ray diffraction technique.In the study of crystal growth simulation,It was found that the influence of InP melt convection induced by crucible rotation was so strong,while the rotation of crystal has little effect on InP melt.In the case of constant crystal rotation speed,with the crucible rotation speed increased,the solid-liquid interface was convex to crystal melt;with the increase of crystal rotated speed,the solid-liquid interface was concave to melt.The melt was more stable when crucible rotation speed at 10 r/min and crystal rotation at 5-10 r/min.In the study of crystals grown from In-riched melt,we analyzed why the indium inclusions was paralleled to <011> directions,we think that indium inclusions were formed between the cellular facets,and facets of the crystal growth interface was along the <011> directions.We also analyzed how the crystal rate growth rate effect the formation of indium inclusions.It was believed that there was a critical rate,when the crystal the growth rate was greater than the critical rate then indium inclusions was formed,otherwise it was not very easy to form inclusions.Huber corrosion and XRD showed that the Indium inclusions cause dislocations easily and make the crystal quality worse.,and damage the quality of the crystals.Hall test shows that the iron concentration of tail ingot of InP which was grown from Indium riched melt was lower than the near stoichiometric one,and the mobility of ingots tail grown from indium riched melt was low.PL-mapping shows that the presence of indium inclusions in crystal may lead to a larger band gap around it.In the study of the crystals which was grown from phosphorus riched melt,we analyzed how the pores grew up,It was because that the heat under pores was not easy to escape,causing the melt temperature under pores were higher than the surroundings,so the region on both sides of pores were rapid grown.Dislocation corrosion showed that the density of dislocation is higher around pores,and the dislocation density was lower far away from pores,the XRD test showed that the crystal quality of pores regions of the wafer was very poor.