Homoepitaxial Single Crystal Diamond Growth By Chemical Vapor Deposition

In this paper,homoepitaxy growths of single crystal diamond respectively on(100),(110)and(111)face have been studied using homemade microwave plasma CVD reactor.The research contends include as following:Firstly,homoepitaxial growth of single crystal diamond on(100)face is studied.The role and mechanism of H2/O2 plasma etching on diamond is analyzed.Researching the effects of methane concentration,substrate temperature and deposition pressure on the optical emission spectrum(OES)of plasma and growth of single crystal diamond are discussed.And then the impact of CVD and HTHP substrate on the growth of single crystal diamond are also studied.The results show that etching pits of tetrahedron of inversion pyramid will expose on the etched(100)face,and deep and large etching pits is due to the wide of dislocation area;The changes of substrate temperature will not influence the concentration of plasma group,and it only changed in the process of chemical reaction kinetics.The growth rate increases with the increase of substrate temperature,but high or too low substrate temperature will deteriorate the quality of the diamond;the spectrum intensities of C2,H?,H? and CH increase with the increase of methane concentration,and that of C2 increases observably while that of H? stays the same.The rising of carbon group concentration improves the diamond growth rate,but it deteriorates the diamond quality.The spectra peak strengths of the every radicals of the plasma increase with the increase of working pressure,and as a result it improves the diamond growth rate while not reduce the diamond quality.Single crystal diamond of the water-clear can be grown on the both CVD and HTHP substrate,but the growth of single crystal diamond on HTHP substrate includes a few of micro-facts,and appearing structure of non-epitaxial,while CVD substrate not exists this question.On the basis of the above study,we use the best parameter to homoepitaxially grow a colorless transparent single crystal diamond on CVD substrate.The growth rate reaches25 ?m/h,SEM picture indicates that the diamond exhibits very good morphology,and it not appears non-epitaxial.The Raman spectrum shows that the diamond quality is higher.Secondly,homoepitaxial growth of single crystal diamond on(110)face is studied.The influence of methane concentrations on the growth rate of(110)face is researched and also compared with(100)face.The characteristics of the growth of(110)face is analyzed.The results show that the growth rate on the(110)crystal face is higher than the(100)face under the same conditions.This result is due to the difference of growth mode in different crystal face.The samples present appearance of asymmetric tetrahedron on(110)face,it composes of the(100)and(113)micro-facets,and the quality of diamond growing on the(110)face is excellent.However,during the growth of diamond,the macro morphology of(110)face is changed,there are other micro-facet appear at the side of the substrate,and the center area of(110)is decrease clearly.It indicates that the(110)face is unfit for the growth of large single crystal diamond.Thirdly,homoepitaxial growth of single crystal diamond on(111)face is studied.We analyze the influence of the methane concentration,substrate temperature,and the substrate of small angle deviation from(111)face on the quality and morphology of diamond.The results show that the disorder poly-crystalline diamond growth is observed under the growth condition of high deposition temperature and high methane concentration.The quality and morphology of the diamond significantly improve with the decreasing of temperature,and a perfectly single crystal growth was obtained at lower substrate temperature with rough surface morphology.Further reducing methane concentration is helpful for epitaxial single diamond growth of high quality and smooth surface;Comparative experiments find that good quality of single crystal diamond can also be grown on the substrate surface deviation(111)faces about 6o under the high temperature and high methane concentration.