Study On Si-GaAs Crystal Dislocation Cell Structure And Microdefects

GaAs is a important compound semiconductor, it has two mainly purpose: One is SI-GaAs micro-elertronics devices, and the other is photoelectron. The liquid encapsulated Czochralski technique for growing GaAs is receiveing considerable attention because it is capable of producing, at reasonable cost, large diameter semi-insulating GaAs has a use in the production of GaAs integrated circuits, and for this application it must have uniform properties over the whole area of a wafer cut from a grown crystal. Substrate slices of uniform electrical properties are necessary for integrated circuit device fabrication. At present there are variations in electrical properties across substrate slices. These are associate with deep levels, in particular EL2, which is generally attributed to antisite defect complexes and considered to be related to grown-in dislocations formed by thermal stresses.In this project we use etching method X-ray transmission and TEM observe and study the form mechanism of cell structure and linear structure; Use SEM observe cell structure directly and evaluate effect to the electrical properties of substrate; At last, use high resolution TEM and EDS to observe and identify the nature of microdefects.This project is mainly provide a way for material and device worker of acquaintance the control of the effect of crystal defects to quality of device, make them improve the progress of crystal growth, improve crystal and device quality.