Preparation And Quantum Manipulation Of Color Centers In Silicon Carbide

Silicon carbide is a class of wide gap semiconductor materials,which is broadly used in the industries of microelectronics,aerospace,high-power devices,et al.Sili-con carbide has mature techniques of single crystal growth,micro-nano processing and doping.In recent years,color centers in silicon carbide have attracted more and more attention due to their advantages of near-infrared fluorescence radiation,long spin co-herence time and ease of integration.Similar to NV centers in diamond,color centers in silicon carbide play an important role in some applications,such as quantum computa-tion,quantum communication,quantum precision measurement,and so on.Moreover,the silicon carbide color centers based quantum devices have many advantages in quan-tum network based on optical fiber transmission,in vivo biological structure detection,large-scale integration and compatibility with existing semiconductor technology.In my postgraduate stage,I mainly studied the preparation,coherent control and applica-tion of color centers in silicon carbide.The main research results of this thesis are as follows:1.The preparation of room temperature single photon sources with high brightness and their applications in quantum information.We experimentally realized room temperature single photon sources with visible light wavelength based on the carbon antisite-vacancy pair defect(CSiVC)in 4H-silicon carbide,stable single photon sources in the near C-band range at elevated temperature based on the color centers in 3C silicon carbide and room temperature single photon sources based on gallium nitride covering visible and near-infrared wavelengths.In ad-dition,the single photon sources were used for fundamental physics research-In our experiment,the single photon source and linear optical devices were used to construct an open system,and the non-unitary Lorentz transformation whose Hamiltonian satis-fies the anti-PT-symmetry was realized.The experimental simulation of the dynamic evolution of boson-Bogolibov quasi-particles in the superflow system was further real-ized.2.Controllable preparation of single silicon vacancies in silicon carbide and coherent manipulation of corresponding defect spin ensembles.In our experiment,we achieved the controllable preparation of single silicon va-cancy spin defects in silicon carbide through techniques including electron beam lithog-raphy,ion implantation and annealing at high-vacuum environment.The conversion efficiency of silicon vacancy defects is up to 80%,which is the highest value reported for the solid-state system.The optical properties of single defects at room temperature were studied.The silicon carbide samples with high concentration of silicon vacancies were prepared and used to realize the quantum sensing of magnetic field with a high sensitivity.3.Depth control of silicon vacancy defects in silicon carbide with nanoscale precision.In our experiment,we achieved selective etching of silicon carbide surface with nanoscale precision by reactive ion etching,and confirmed that the etching method has small impacts on the silicon vacancy defects near surface.The reactive ion etching and a home-built confocal microscopy were used to reconstruct the depth distribution of silicon vacancy defects generated by ion implantation with different energies and types of elements.The influences of depth on the spin and optical properties of the shallow silicon vacancy defects were studied.This work lays a foundation for the practical applications of probing external sample spins and magnetic resonance imaging.4.Controllable preparation of single divacancy defects in silicon carbide and coherent manipulation of single spin at room temperature.In this work,We controllably prepared arrays of single divacancy in 4H-silicon carbide.We demonstrated the room temperature coherent manipulation of single di-vacancy for the first time.The ODMR contrast and fluorescence intensity of single defects at room temperature are the highest compared with other reported types of spin defects in silicon carbide so far,and even be comparable with those of NV centers in diamond.This is the second solid state defect qubit that exhibits such unique properties in terms of high spin readout contrast together with high photon counts at room temper-ature,discovered after NV center in diamond.In addition,the coupling between a single electron spin with its neighbor 29Si nuclear spin was measured,which will be helpful for the preparations of the complex entangled states of photon-electron spin-nuclear spin,and may promote the development of the silicon carbide defect spin system in the applications of quantum information.