Study On Growth Of Single Crystal Diamond By 75 KW,915 MHz MPCVD Reactor

Diamond has excellent physical and chemical properties in many areas,including mechanics,heat,optics,acoustics,electricity,chemistry,and so on,giving it a wide range of applications.Because of its high plasma density,wide operating pressure range,electrodeless discharge,and pure plasma environment,microwave plasma chemical vapor deposition（MPCVD）is currently considered the preferred method for preparing high-quality single crystal diamond.However,due to its limitations,the 2.45 GHz MPCVD device cannot prepare high-quality single crystal diamond in large quantities,whereas the 915 MHz MPCVD device can meet the conditions for mass deposition of high-quality single crystal diamond,but its research is less extensive.In light of this difficulty,the high-quality and batch deposition of single crystal diamond was investigated using a laboratory-built 75 k W and915 MHz MPCVD device.The following are the specific research contents:1.The effects of methane concentration and microwave power on single crystal diamond deposition quality were investigated.The results show that as methane concentration decreases and microwave power increases,the growth surface of single crystal diamond begins to exhibit a layered growth morphology with complete morphology,regular structure,and uniform step spacing,and the growth rate of homogeneous epitaxy of single crystal diamond increases significantly with microwave power and decreases with methane concentration.2.The effect of substrate temperature on single crystal diamond deposition quality was investigated.The results show that the substrate temperature has a significant impact on the growth rate,deposition quality,and surface morphology of single crystal diamond in a 35 k W high-power microwave plasma environment.When the microwave power is 35 k W,the methane concentration is 3%,and the substrate temperature is 950°C,a single crystal diamond of high quality and color can be prepared.3.The 915 MHz MPCVD device’s airflow field and microwave electric field are simulated.The results show that when the hydrogen flow rate is 2000ml/min,the fast flow rate region can effectively cover the substrate platform.At the same time,the number of gas molecules will be doubled,allowing more active hydrogen atoms and carbon containing active groups to be excited during plasma discharge,allowing single crystal diamond to be grown in batch;when the microwave power is increased to 35 k W,the electric field amplitude reaches 2.55×10⁵V/m,and the amplitude of the electric field increases almost linearly with the increase of microwave power,and the range of the strong fiel increases almost linearly with the increase of microwave.4.Different deposition pressures were used in the batch growth of single crystal diamond.The results show that as deposition pressure increases,the plasma ball shrinks and the deposition uniformity changes.When the deposition pressure is 13.8 k Pa,the plasma ball simply"covers"the entire substrate platform area,allowing good quality single crystal diamond to be deposited at the edge and middle of the substrate platform.5.Finally,under the process conditions of 3%CH₄,13.8 k Pa,and 35 k W,uniform growth of 60 single crystal diamonds was achieved.The deposition quality was excellent,as was the uniformity of deposition quality and growth rate.