Research On The Defects Of The Epitaxial Growth Of Single Crystal Diamond

In this paper,microwave plasma chemical vapor deposition method was used to study the effects of diamond temperature and methane concentration on single crystal diamond defects in the homoepitaxial growth of single crystal diamond,and the phenomenon of single crystal diamond expansion was explored.Specific studies include the following three aspects:1.Homogenous epitaxial growth experiments were performed on single crystal diamond seed crystals containing defects,and the temperature of single crystal diamond seed crystals was changed under the condition that other deposition parameters remained the same,through SEM,plasma emission spectroscopy,Raman spectroscopy,and XRD and other characterization methods analyze the influence of seed temperature on the defect change of monocrystalline diamond homoepitaxial growth.It was found that the higher the temperature of the single crystal diamond,the higher the spectral intensity ratio I?C₂?/I?H_??corresponding to the C₂ and H_?groups in the plasma emission spectrum of the diamond surface,and the lower the electron temperature of the plasma.The collision between particles in the body is more intense.Single crystal diamond growth rate rises with increasing seed temperature.The single crystal diamond defects before and after growth were characterized by SEM.When the seed temperature was too low,the cracks from the defects appeared after homoepitaxial growth on the surface of the single crystal diamond;the temperature was moderate at the seed temperature?780-820°C?,the surface defects of single crystal diamond are inhibited and covered,and the defect area is reduced.In the case of high seed temperature,the defect area is enlarged and the protrusion is more obvious.Through the SEM characterization of the single crystal diamond of the cross-section,it was found that the origin of the defect was a convex point on the surface of the diamond,and the defect continuously expanded during the deposition process.The Raman test of the single crystal diamond cross section and growth surface after homogeneous epitaxial growth shows that the quality of single crystal diamond grown at lower and higher seeding temperatures is poor,and the diamond characteristic peak gradually shifts to low wave numbers.The tensile stress increases,while the single crystal diamond grown at a moderate seeding temperature has a good quality,and the diamond has a small Raman peak shift and a small stress.It was also found through XRD test characterization that the single crystal diamond grown at moderate seed temperature has a low FWHM and good quality.Finally,homogenous epitaxial growth of seed crystals with moderate seed crystal temperatures on defect-free single crystal diamond seed crystals results in a single crystal diamond with high transparency and smooth surface.2.In the homoepitaxial growth of single crystal diamonds containing defects with different concentrations of methane,the emission spectrum shows that with the increase of the methane concentration,the intensity of plasma emission spectrum of the diamond surface related to the C₂ and H_?groups increases.The corresponding spectral intensity ratio I?C₂?/I?H_??is higher,and the temperature of the electrons increases,and the collision between the particles in the plasma is less intense.Through SEM and metallographic microscopy,it was found that except for the 4%methane concentration,the defect area did not increase,and the defect area and the defect bulging degree increased significantly in other methane concentrations.According to Raman spectroscopy,it was observed that as the concentration of methane increased,the characteristic peak of diamond shifted toward low wave numbers,the tensile stress showed an increasing trend,and the amorphous carbon peak also increased,reflecting that the higher the methane concentration,the higher the single crystal,the worse the diamond quality.Combined with the test characterization results,the increase in methane concentration is not conducive to inhibiting the growth of defects in single crystal diamond,while the low methane concentration is conducive to inhibit the expansion of defects,low methane concentration can guarantee the quality of single crystal diamond growth,but the growth rate is slow.3.The expansion of single crystal diamond was studied.Using the optimized single crystal diamond epitaxial growth conditions,the single crystal diamond 2D expansion is realized on a 7×7×0.55mm³seed crystal by chamfering the growth surface of the single crystal diamond growth surface and the depth of the substrate holder.The growth was expanded to obtain a single crystal diamond with a thickness of 1.5 mm and a size of 8.6 x 8.6 mm²,with a growth rate of 20?m/h.The analysis shows that by chamfering the four sides of the single crystal diamond,the temperature at the chamfering surface can be similar to the growth surface temperature,and polycrystalline growth at the edge due to the high deposition temperature can be avoided.Single crystal diamond seed plane is slightly higher than the substrate support surface?0.1mm?,which is conducive to uniform plasma concentration on the surface of single crystal diamond seed crystals and is conducive to lateral growth.A proposal was made for the expansion of single-crystal diamond.