The Influence Of Carbon Dioxide On The Growth Of Single Crystal Diamonds By Microwave Plasma CVD

Single crystal diamond attracted many researchers'attention because of its excellent properties. However, limited by their size, doping and cost, natural and high-pressure high-temperature (HPHT) diamonds are unsuitable for applications. Single crystal diamond growth synthesized by MPCVD technique becomes the most promising method.In this work, CO2 was generally introduced in the reaction atmosphere (H2:CH4:N2=500 sccm:60 sccm:1.8 sccm) with different flow rate(0 sccm,10 sccm,20 sccm,25 sccm,30 sccm) to synthesize homoepitaxy single crystal diamonds. The samples were tested by microscopy,AFM, Raman, photoluminescence (PL), UV,optical emission spectroscopy (OES),and IR.It comes to the conclusion that C and O interact while inducing CO2, which varies the growth rate. The groeth rate comes to maxmum (70μm) when adding 20 sccm CO2.While the quality of samples do not show any obvious change, which is proved by slim varyfy in Raman FWHM. The surface roughness of sample turned to minimum at 1.1 nm with 10 sccm CO2 adding. The surface roughness and the color are both in respect to the N-related content. The less N-related content in the sample, the lighter the color is, and the smoother the surface is. The OES and PL also support this point. The seed and sample do not have any transmission in the ultraviolet range and the sample with adding 30 sccm CO2 showed a maximum transmission about 50%, which doubles the sample without CO2 adding. IR can detect the characteristic peak of diamond. Comparing to O2 ,N2 ,and both of them doped, CO2 can enhance the growth rate and smooth the sample surface, which is the optimize choice for sample crystal diamond growth.