Theoretical Study Of Photoemission Based On Secondary Electron Emissio

Secondary Electron Emission（SEE）and photoelectric emission are closely related to our lives,and has great research value.Nowadays research on both focuses on material manufacturing and applications,such as photocells,image intensifiers and scanning electron microscopes,but less research on the basic theories of both.Because SEE and photoelectric emission have a common physical mechanism for the transport and escape of excited electrons,the basic theory of photoelectric emission can be studied based on SEE,and the main research content is as follows:（1）The photoelectric emission mechanism of metals is relatively simple,and the study of it is conducive to promoting the study of photoelectric emission of complex materials such as semiconductors and insulators.Photoelectric Sensitivity（PS）and Quantum Efficiency（QE）are physical quantities that characterize the efficiency of photoelectric emission,and the larger the PS or QE,the higher the efficiency of photoelectric emission.In this paper,the Electron-induced Secondary Electron Model（ESEM）is established by combining the physical processes of SEE and photoelectric emission,related theoretical models and experimental data,based on which the cut-off frequencyγ₀（about[γ₀,1.55γ₀]）,temperature T≤1100 K and applied electric fieldξ≤1×10⁶V/cm are obtained Analytical formula of PS and QE under the condition of photoelectric emission on metal surfaces.Compared with the traditional Fowler-Du Bridge model and three-step model,the ESEM model has the advantages of wide application,ease of use and full consideration of temperature factors.（2）The conduction band bottom energy level E_c of Negative Electron Affinity Semiconductor（NEAS）is higher than that of vacuum energy level E₀,so its effective electron affinity is negative,and it has the characteristics of high quantum efficiency,uniform spectral response,concentrated photoelectron energy distribution and small thermal electron emission when used as a photocathode,so it has great research value.In this paper,a new SEE model suitable for NEAS with Large Mean Escape Depth（NEASLD）with large average escape depth of secondary electrons is constructed,which can be used to calculate the relevant parameters and secondary electron yield of NEASLD when the primary electron energy is greater than 10.0ke V,and pave the way for the study of NEAS photoelectric emission.（3）For a given NEAS,NEASLD is NEAS with Large Mean Escape Depth of Photoelectrons（NEASLP）.Therefore,the model of NEASLD can be used to study NEASLP,and theλ_phl and B_phflat of NEASLP’s photoelectric emission are calculated(λ_phl is the average depth of escape of photoelectrons generated by photons with energies greater than(h_pγ₀+2.4×10^-20J),B_phflat is the B_ph of NEASLP in the range of[(h_pγ₀+2.4×10^-20J)/h_p,γ_h-flat,B_phis the probability that electrons excited by photons in NEASLP will enter a vacuum after reaching the surface,andγ_h-flat is the maximum value of theγin the flat part of the spectral response curve,h_pis Planck constant.)After comparison with experimental data,it can be seen that the formula of SEE and photoelectric emission derived in this paper has high accuracy.The main significances of this study are:1)、The research of this paper deepens the understanding of the physical process of SEE and photoelectric emission and enriches the theory of SEE and photoelectric emission;2)、The theoretical formulas derived in this paper can be used to calculate the relevant parameters,which can replace specific experiments and reduce research cost;3)、The researchers can use the theoretical formulas derived in this paper to check the experimental data.