The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E_0.For the cylindrical inclusion with gradient dielectric function,ει(r)=b+cr,random...The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E_0.For the cylindrical inclusion with gradient dielectric function,ει(r)=b+cr,randomly embedded in a host with dielectric constant εm,we have obtained the exact solution of local electric potential of the composite media regions,which obeys a linear constitutive relation D=εE,using hypergeometric function.In dilute limit,we have derived the effective dielectric response of the linear composite media.Furthermore,for larger volume fraction,the formulas of effective dielectric response of the graded composite media are given.展开更多
Based on the k.p theory of Luttinger-Kohn and Bir-Pikus,analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained.Strain effects on valence band edges and hole effective masses in s...Based on the k.p theory of Luttinger-Kohn and Bir-Pikus,analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained.Strain effects on valence band edges and hole effective masses in strained wurtzite ZnO materials are also discussed.In comparison with unstrained ZnO materials,apparent movement of valence band edges such as "light hole band","heavy hole band" and "crystal splitting band" at Γ point is found in strained wurtzite ZnO materials.Moreover,effective masses of "light hole band","heavy hole band" and "crystal splitting band" for strained wurtzite ZnO materials as the function of stress are given.The analytical results can provide a theoretical foundation for the understanding of physics of strained ZnO materials and its applications with the framework for an effective mass theory.展开更多
Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source....Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source. The experiment of the emission and excitation optical spectrum, decay curve of fluorescence and residuals for several sensitive materials confirms the match of Y2O2S:Eu using the light source and the feasibility of the system. The rare earth material Y2O2S:Eu is selected as the material candidate for being the most sensitive.展开更多
Due to the coupling of piezoelectric and semiconducting dual properties,much attention has been focused on the piezoelectric semiconductor materials,such as ZnO,ZnS,CdS and GaN.With the usage of these piezoelectric se...Due to the coupling of piezoelectric and semiconducting dual properties,much attention has been focused on the piezoelectric semiconductor materials,such as ZnO,ZnS,CdS and GaN.With the usage of these piezoelectric semiconductor materials,novel nanodevices have been demonstrated,from which a new field called piezotronics was formulated.The core of piezotronics is to study the mechanism of the piezoelectric effect on tuning the charge transport behavior across various junctions or interfaces,with potential applications in sensors,microelectromechanical systems,and force/pressure triggered electric devices.Here following the theoretical frame work of piezotronic effect,analytical solutions of piezoelectric heterojunction are presented to investigate the electrical transport behavior at a p-n junction.Numerical simulation is given for guiding future experimental measurements.展开更多
文摘The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E_0.For the cylindrical inclusion with gradient dielectric function,ει(r)=b+cr,randomly embedded in a host with dielectric constant εm,we have obtained the exact solution of local electric potential of the composite media regions,which obeys a linear constitutive relation D=εE,using hypergeometric function.In dilute limit,we have derived the effective dielectric response of the linear composite media.Furthermore,for larger volume fraction,the formulas of effective dielectric response of the graded composite media are given.
基金supported by the National Natural Science Foundation of China (Grant Nos.60776034,61162025)the Youth Scholar Training Plan of Tibet University for Nationalities (Grant No.13myQP10)the Major Program Training Plan of Tibet University for Nationalities (Grant No.12myZP02)
文摘Based on the k.p theory of Luttinger-Kohn and Bir-Pikus,analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained.Strain effects on valence band edges and hole effective masses in strained wurtzite ZnO materials are also discussed.In comparison with unstrained ZnO materials,apparent movement of valence band edges such as "light hole band","heavy hole band" and "crystal splitting band" at Γ point is found in strained wurtzite ZnO materials.Moreover,effective masses of "light hole band","heavy hole band" and "crystal splitting band" for strained wurtzite ZnO materials as the function of stress are given.The analytical results can provide a theoretical foundation for the understanding of physics of strained ZnO materials and its applications with the framework for an effective mass theory.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50775198, 60102002, 60974115 and 60977061)the Youth Foundation of Education Bureau of Hebei Province (Grant No.2011225)
文摘Based on the optical properties of rare earth fluorescence materials, a set of fluorescence optical fiber systems was designed. The system selects the emitting LED, which is economical and practical as a light source. The experiment of the emission and excitation optical spectrum, decay curve of fluorescence and residuals for several sensitive materials confirms the match of Y2O2S:Eu using the light source and the feasibility of the system. The rare earth material Y2O2S:Eu is selected as the material candidate for being the most sensitive.
基金partly supported by the Beijing Institute of Nanoenergy and NanosystemsChinese Academy of Sciencesthe Fundamental Research Funds for the Central Universities(Grant No.Lzujbky-2013-35)
文摘Due to the coupling of piezoelectric and semiconducting dual properties,much attention has been focused on the piezoelectric semiconductor materials,such as ZnO,ZnS,CdS and GaN.With the usage of these piezoelectric semiconductor materials,novel nanodevices have been demonstrated,from which a new field called piezotronics was formulated.The core of piezotronics is to study the mechanism of the piezoelectric effect on tuning the charge transport behavior across various junctions or interfaces,with potential applications in sensors,microelectromechanical systems,and force/pressure triggered electric devices.Here following the theoretical frame work of piezotronic effect,analytical solutions of piezoelectric heterojunction are presented to investigate the electrical transport behavior at a p-n junction.Numerical simulation is given for guiding future experimental measurements.