Effective Generation Method And Application Of Two-dimensional Hexagonal Boron Nitride-based Single Photon Sources

Solid-state single photon sources have important application prospects in the fields of quantum communication,optical quantum information processing and quantum computing.Single photon sources based on two-dimensional materials can achieve high photon extraction rate and are easier to integrate into photonic circuits,thereby becoming a research hotspot in the field of single photon sources.Two-dimensional hexagonal boron nitride(2D-hBN)is the only two-dimensional host material that can emit single photons at room temperature,and the emission wavelength of 2D-hBN-based single photon sources covers almost the entire visible wavelength range(380nm-780nm).It is an important candidate for high performance single photon sources.However,the current research of 2D-hBN-based single photons faces various challenges:(1)there is no reliable method for effectively generating 2D-hBN single photon sources;(2)the related applications of 2D-hBN single photon sources are still under investigation;(3)the electrically driven 2D-hBN single photon emission structure has not been achieved.In response to the above problems,this paper has done the following research:(1)Two-dimensional 2D-hBN samples were irradiated by heavy ion(Ge~+,Ta~+)with different doses.The PL data of the samples after irradiation showed that heavy ion irradiation(Ge~+and Ta~+)can effectively generate single photon sources in the central region(non-wrinkle or edge)of 2D-hBN,and the optimal ion beams irradiated by Ge~+and Ta~+were 3×10~94)9)/(88)~2·and1×10~84)9)/(88)~2·,respectively.The atoms in the irradiated region obtain enough energy to escape from the normal lattice position in 2D-hBN,resulting in the vacancy defects in which a single electron-hole pair recombined and then emit single photon.When the ion beam is less than the optimal dose,it can not effectively generate single photons related defects due to its weakening of damage ability to the 2D-hBN.When the ion beam dose is larger than the optimal dose,it will cause some non-single photon defects in the 2D-hBN due to its large damage ability,which will lead to a large background emission,or even submerge the single photon emission,thus making the purity of single photons decreases.In addition,the number and purity of single photons generated by Ta~+irradiated samples are higher than that of Ge~+irradiated samples,mainly because the damage ability of Ta~+at the same dose level(LET value is 60)is higher than that of Ge~+irradiated samples(LET value is 36).This method enables 2D-hBN to generate single photon sources effectively.(2)The response relationship of optical properties of 2D-hBN single photon emission through dielectrics with different refractive index is studied.The results show that the emission wavelength of the same single photon source is red-shifted as the refractive index increases(air n=1.0,deionized water n=1.333,and anhydrous ethanol n=1.361).The maximum sensitivity of peak position change is12.679)8)?(per refractive index unit)and 15.679)8)?when the emission wavelength is around 590 nm and 622 nm,with the highest figure of merit(FOM)6.335 and 7.835,respectively.Because when the electric field of2D-hBN single photon is in the medium with different refractive index,the dielectric constant changes,and its radiation field will change accordingly,resulting in the displacement of the energy level,and then the change of the emission wavelength.Its narrow full width at half maximum(about 5nm),is expected to achieve higher FOM.The application potential of 2D-hBN single photon source as refractive index sensor is revealed,which provides a new idea for the development of its application.(3)The structure of the electrically driven 2D-hBN single photon emission is analyzed theoretically.The structure is designed and the corresponding devices are fabricated.2D-hBN is a good insulation material,it is difficult to realize carrier injection by the usual metal-semiconductor structure,so it is a better choice to realize carrier injection by tunneling effect.Firstly,the simplest electrically driven structure was designed,the"sandwich"structure of graphene electrode/2D-hBN single photon source layer/graphene electrode,this is due to the high carrier mobility of graphene,which is widely used as an electrode in the photoelectric research of 2D materials and has high transparency.It does not affect the external quantum efficiency of the luminescence center in the vertical structure.In addition,the van der Waals heterostructures with five layers of 2D-hBN/graphene/2D-hBN single photon source layer/graphene/2D-hBN.The reason why the 2D-hBN was added top and bottom is to avoid the decrease of carrier mobility of graphene caused by external environment.This study can provide a reference for the structure design and implementation of an electrically driven 2D-hBN single photon emission.