Study On Multi-phonon Resonance Raman Scattering Process And Enhancement Mechanism Of ZnS:In³⁺/ZnS:Ag⁺ Nanoparticles

Semiconductor materials and related principles and technologies are the cornerstones of modern information society.Resonance Raman spectroscopy is an important means to explore the electronic band structure of semiconductor materials and the relationship between phonon dispersion in Brillouin zone,especially in the study of carrier relaxation dynamics of II-VI semiconductors.In this paper,ZnS,a wide band gap semiconductor,is taken as the research object.By doping ZnS nanoparticles with In³⁺,Ag⁺and Cu²⁺with different ion radii,the lattice and energy band structure of ZnS are modulated,and the selective enhancement of multi-order longitudinal optical（LO）phonon modes of ZnS is realized.Raman spectra and photoluminescence spectra of ZnS and ion-doped ZnS nanoparticles were obtained under the excitation light of 325 nm wavelength.The multi-phonon Raman scattering process of ZnS was analyzed through experimental data,and the influence of ion doping on resonance enhancement mechanism was revealed by using Fr（?）hlich electron-phonon interaction mechanism.The main results are as follows:（1）By doping ZnS with In³⁺,the resonance enhancement of the phonon mode intensity of the evil hunting LO in its Raman spectrum is realized.When the In³⁺doping concentration is 0.08%,the resonance Raman scattering intensity of ZnS is about 3.4 times higher than that of undoped ZnS.According to the data,the influence of In³⁺doping on the resonance Raman scattering process of ZnS was analyzed.Based on Fr（?）hlich’s electro-phonon coupling mechanism and cascade emission model,the contribution of lattice distortion caused by In³⁺doping to LO phonon emission process is analyzed.The ZnS:In³⁺nanoparticles were functionalized.With its strong anti-interference ability of multi-phonon resonance Raman scattering,the sandwich biological detection strategy was constructed.Carcinoembryonic antigen was selected as the model to be detected,and the application of ZnS:In³⁺nanoparticles in biomarker detection was demonstrated in principle.The detection sensitivity could reach 1 pg/m L.（2）Doping ZnS nanoparticles with Ag^+.Several concentrations were selected for doping,and it was found that when 1.5%Ag⁺was doped,the 1LO intensity of resonance Raman scattering was enhanced by about 2.6 times than that of pure ZnS.Combined with other characterization analysis,the enhancement mechanism is that Ag+doping replaces the lattice position of Zn²⁺and causes local lattice distortion nearby.Because Zn²⁺leaves the equilibrium position and produces relative displacement,the atomic vibration mode is enhanced,and the number of phonons is increased.The doping of Ag⁺also leads to the spatial localization of more electrons,which are bound to high-concentration defects formed by S vacancies and are more easily coupled with phonons.（3）Cu²⁺with a radius close to that of Zn²⁺was also selected to dope ZnS nanoparticles as a control sample.Through data analysis,it is found that because the radius of doped Cu²⁺is close to that of Zn²⁺,the lattice structure does not change obviously,and the resonance Raman scattering intensity of a series of longitudinal optical phonons of ZnS does not increase obviously.