The Microscopic Character And Distributing Of Defects In Large Diameter SI-GaAs

GaAs is a compound semiconductor which has the most rapid development in semiconductor materials. GaAs is used to fabricate the devices and circuits of high frequency and speed because of its high mobility ratio and direct transition energy band structure. SI-GaAs have expansive market demand .The correlation devices have been used to light communication and secondary planet communication and so on. Because the growth technology and quality improvement of single crystal influence the devices development, it is important that the single crystal diameter to get to be enlarged, the defects to be decreased for the the physical parameters and quality uniformity to be improved. So the detects investigation of large diameter SI-GaAs is very important.In this paper, the distribution and pattern and density of detects in 6-inch SI-GaAs were investigated by mean of chemical etching and microscopy observation, etc. The detects were displayed by mean of AB etching and molten KOH etching; Different patterns of dislocation and microdefect were found when the etched samples were checked and observed by metalloscope and scanning electron microscope and so on. The whole defects distribution of sample was studied using PL Mapping technique in detail, and the sample uniformity was checked. The microscopic characterization of detects and formation mechanics were investigated.The experimental results showed that there are cell structures, netted structures in the sample surface, and so on. By analyzing the etching morphology of dislocations and micro-defects, it is indicated that their relationship are close and they are interactional. Furthermore, with the etching time extending, the defects with other patterns were found, which belong to the particular defect structures, for example the circularity dislocations. The distribution of dislocation density is U shape along the direction of diameter; The formation of defects in large diameter SI-GaAs was discussed which have some contacts with crystallography orientation and sample grown technology. The conclusions is very useful for the producers of material and device understand the defects effect on the quality of devices and materials.