Study On The Formation Mechanism Of Diamond Germanium Vacancy Color Center And Experimental Preparation

As an excellent single photon source,diamond vacancy color centers have the advantages of photostability and biocompatibility,and are widely used in the fields of encrypted information transmission and bioluminescent labeling.At present,the most widely studied vacancy color centers are diamond NV color center and SiV color center.As a single photon source that can be polarized and read by laser,single NV color center is a very good solid-state spin system.However,due to its large spectral width and long lifetime of excited states,it is not conducive to the application of quantum communication.Compared with NV color center,the emission peak of SiV color center is located in the near-infrared region,with wide half peak width and high emission intensity,but the emission efficiency is not high.The research shows that the structure and luminous intensity of GeV color center and SiV color center are similar in diamond,and GeV has luminous efficiency higher than SiV color center.Therefore,the research on the formation mechanism and experimental preparation of GeV color center are of great significance to the development of quantum communication.In this thesis,the formation process of GeV color center is simulated by first principles :(1)the adsorption and migration process of Ge atoms on(001)diamond surface is calculated.Eight different diamond surface models were established.The adsorption energy calculation shows that Ge atoms cannot be adsorbed on the surface of all-hydrogen terminated diamond,but can be adsorbed on the surface of non-all-hydrogen terminated diamond.With the increase of the number of hydrogen defects,the overall adsorption energy also increases.Therefore,the number of hydrogen defects on diamond surface may determine the content of Ge element on diamond surface.It is found that charge transfer occurs between Ge atom and carbon atom on diamond surface after electron structure calculation and analysis.(2)Ge atoms deposited on the diamond surface will enter the diamond crystal with the growth of diamond.Molecular dynamics is used to dynamically simulate the process of Ge atoms combining with vacancies to form GeV color centers.It is found that Ge atoms cannot migrate in a long distance in diamond body,but arrive near Ge atoms through vacancy migration,so that the two can combine to form GeV color center.Secondly,in order to discuss the influence of impurity atoms on the fluorescence luminescence of diamond GeV color center,the co-doping model of GeV color center and impurity H,B,Si,O,N was constructed.The binding energy,energy band and state density of the co-doping model were analyzed.It was found that the incorporation of impurity atoms would lead to blue shift of the fluorescence peak of GeV color center.Finally,diamond film containing GeV color center was successfully prepared on quartz substrate by solid substitution method,substrate method and MPCVD device.Due to the influence of impurity elements,NV0 and SiV-color center can be detected in the undoped diamond film by fluorescence detection equipment.However,when Ge element is added,NV0 and SiV-color center can be detected.The GeV color centers of diamond films prepared by the two methods were detected at ZPL=603.9nm and 604.6nm,respectively.