Two-Dimensional Expansion Of Single Crystal Diamond Growth

In this paper,microwave plasma chemical vapor deposition?MPCVD?method was used to study the homogeneous epitaxy growth of single crystal diamond,especially the influence of different angle inclined surface of the edge of single crystal diamond sample and the structure of substrate base on the two-dimensional area expansion of single crystal diamond during the growth process.At the same time,the preparation of high quality single crystal diamond was studied in depth.Specific research includes the following three aspects:1.Study on the preparation of high quality and thick single crystal diamond.The effect of growth temperature on defects and stress of single crystal diamond was studied.The results show that the defects on the surface of single crystal diamond tend to be suppressed and covered when the seed temperature is about 820?.Meanwhile,the Raman peak shift is smaller and the total stress is smaller than other temperatures.It is suitable for obtaining thick single crystal diamond with high transparency and smooth surface.2.The effect of inclined surfaces at different angles on the two-dimensional area expansion of single crystal diamond was studied.The edge of single crystal diamond ?100? was polished by a fine laser cutting and polishing machine.The inclined surface deviating from ?100? crystal plane at different angles was formed and then homogeneous epitaxy was carried out.The plasma changes near the inclined surface of ?100? crystal plane edge were detected by spectrometer.The edge morphology of samples was observed by binocular diamond microscope to study the different angles of single crystal diamond edge.The effect of gradient and inclination on its two-dimensional area enlargement.The results show that the slope angle of the edge surface of single crystal diamond has an effect on the growth quality of single crystal epitaxy at the edge.The samples with the slope angle between 0.8° and 11.3°show typical layered step growth pattern of single crystal diamond on the edge surface,and the step width decreases with the increase of the slope angle.At the same time,with the increase of the inclined plane angle,the number of polycrystalline diamond defects in the growing area enlarged around the sample decreases first and then increases.At the inclined angle of 3.8°,the number of polycrystalline diamond defects in the growing area enlarged is the least,and the two-dimensional enlargement shows a complete single crystal diamond epitaxy growth characteristic.The measurement of the spectral intensity of C₂ and H?groups in the plasma emission spectra at the edge of single crystal diamond shows that the content of C₂ groups in the plasma varies greatly when the inclined plane angle is 3.8°.According to the characterization analysis,single crystal diamond with 3.8° inclined plane is suitable for two-dimensional area expansion mainly because the electric field intensity around the sample is weakened,and the number of carbon-containing precursors reaching the edge of single crystal diamond decreases and is less than the critical concentration of step formation.3.The effect of substrate structure on the two-dimensional area expansion of single crystal diamond was studied.The effect of the difference between the groove depth in the substrate and the sample thickness on the two-dimensional area enlargement is discussed.The experimental results show that when the thickness of single crystal diamond with vertical prism is greater than or equal to the groove depth,due to the influence of edge effect,more polycrystalline diamonds are produced around it,which is not conducive to the expansion of its two-dimensional area.As the groove depth increases with the constant thickness of single crystal diamond,the number of edge polycrystalline diamonds decreases gradually,which is suitable for the epitaxy growth of single crystal diamond.However,the growth rate decreases obviously.By comparing the quality of the grown diamond,it is found that the two-dimensional area of single crystal diamond can be enlarged when the groove depth in the substrate is 1 mm different from the sample thickness.It is believed that with the increase of groove depth,the electric field intensity near the edge will be changed,plasma density will be reduced,which is similar to the growth conditions inside single crystal diamond,and is beneficial to the epitaxy growth of single crystal diamond.However,excessive groove depth will reduce the number of active groups reaching the surface of diamond in plasma,and affect the growth rate of diamond,which is not conducive to single crystal growth.Two-dimensional enlarged growth of diamond.