Properties Of Resonant Excitation Spectra Of Single Erbium Ions In Silicon

Erbium ion,as one of the rare-earth ions,possesses telecom-band wavelength optical transitions as well as optically addressable spins.One of the frequently-used host materials for erbium ions is silicon.Silicon has been widely used in micro-electronics and integrated photonics with well established micro/nano fabrication and isotope purification technologies on an industrial scale.With the above advantages,erbium-doped silicon is a promising material system for quantum computing and quantum communication.However,erbium forms a number of sites in silicon and each site has unique symmetry and transition wavelength.As a result,the identification and characterization of erbium sites in silicon are pivotal points for material optimization and fabrication of practical devices with a high homogeneity.The most effective method of identifying and characterizing erbium sites is Zeeman spectroscopy.However,identifying and characterizing erbium sites was limited by the large inhomogeneous broadening encountered in the previous spectroscopy study of ensemble ions.Photo-luminescence excitation spectroscopy at a single-ion level avoids the inhomogeneous broadening of ensemble ions,provides high spectral resolution and could accelerate the development of quantum computing and high-precision sensors based on single erbium ions.This dissertation utilizes the ionization process of a single trap which is associated with the excitation and relaxation of a single erbium ion to detect the individual erbium ions in a silicon nano-transistor.The dissertation investigates the Zeeman spectroscopy,site symmetry,spectral linewidth,power broadening and resonant excitation rate for single erbium ions.The main contents of this dissertation are as follows:In order to determine the site symmetry of erbium ions in silicon,the dissertation studies the anisotropy of the Zeeman splitting of a single erbium ion at magnetic fields in different directions and builds a spin Hamiltonian model to fit the spectroscopic data.The fitting results give the electronic Zeeman tensor as well as the hyperfine tensors.The anisotropy and trace of the Zeeman tensors indicate that the specific erbium ion occupied a low-symmetry,distorted cubic site.The dissertation utilizes the spin Hamiltonian model to search for zero-first-order Zeeman magnetic fields of the hyperfine transitions in ground state and estimates the spin coherence times at these fields.Spin coherence times are expected to be larger than one second at 1 T magnetic field.Additionally,this dissertation also presents Zeeman spectra of a coupled pair of erbium ions.In order to characterize the spectral property of single erbium ions,this dissertation develops a three-state Markov-chain model to describe the excitation and photonionization processes for erbium ions in silicon.The rate equations from the Markovchain model indicates that the ionization rate of the single trap associated with the erbium ion is approximately proportional to the excitation rate of the erbium ion under weak excitation.Therefore,the photo-ionization rate can be used to characterize the spectral property of the erbium ion.This dissertation utilizes this method to investigate the spectral linewidth and power broadening.Firstly,the spectra at different powers show Lorentzian lineshapes.Secondly,the linewidth is constant at low powers and increases obviously at higher powers.Finally,this dissertation investigates broadening mechanisms in details.The results suggest that the absorption saturation effect and magnetic noise are negligible in the power broadening and the possible broadening sources are charge noise and heating due to light.The last part of this dissertation focuses on the study of resonant excitation rate of single erbium ion.A time-resolved detection based on single-trap sample,a narrow linewidth as well as a fast resonant excitation are pivotal to spin readout.The optical coherence and nuclear spin relaxation of single erbium ions are also explored at this chapter.