The optical properties of materials are of great significance for their device applications.Different numbers of krypton ions are doped into high-quality Zn-polar ZnO films fabricated by molecular beam epitaxy(MBE)on ...The optical properties of materials are of great significance for their device applications.Different numbers of krypton ions are doped into high-quality Zn-polar ZnO films fabricated by molecular beam epitaxy(MBE)on sapphire substrates through ion implantation.Krypton is chemically inert.The structures,morphologies,and optical properties of films are measured.The x-ray diffraction(XRD)spectra confirm the wurtzite structures of Zn-polar ZnO films.Atomic force microscopy(AFM)results show that the films have pit surface structure and higher roughness after Kr ion implantation.A detailed investigation of the optical properties is performed by using the absorption spectrum,photoluminescence(PL),and spectroscopic ellipsometry(SE).The absorption spectrum is measured by UV-visible spectrophotometer and the bandgap energy is estimated by the Tauc method.The results show that the absorption increases and the bandgap decreases after Kr ion implantation.Moreover,the Kr ion implantation concentration also affects the properties of the film.The ellipsometry results show that the films'refractive index decreases with the Kr ion implantation concentration increasing.These results can conduce to the design and optimization of Kr ion-implanted polar ZnO films for optoelectronic applications.展开更多
Discussions pertaining to enhancement in the luminous efficiency of cesium iodide(CsI)detectors doped with sodium(Na)abound.In this study,the defect structure of one Cs atom replaced by one Na atom is calculated using...Discussions pertaining to enhancement in the luminous efficiency of cesium iodide(CsI)detectors doped with sodium(Na)abound.In this study,the defect structure of one Cs atom replaced by one Na atom is calculated using the ab initio method.Subsequently,the electronic band structures,densities of states,optical absorption spectra,phonons,and transport properties of CsI in perfect and defective structures are investigated.The absorption spectra of CsI with and without Na impurities are compared.It is discovered that the impurity levels in the forbidden band are generated from the shell electron distributions of the impurity atoms,not from lattice distortions.Furthermore,it is discovered that the optical absorption can be enhanced by doping CsI with Na.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11875088)the National Key Basic Research Program of China(Grant No.2015CB921003).
文摘The optical properties of materials are of great significance for their device applications.Different numbers of krypton ions are doped into high-quality Zn-polar ZnO films fabricated by molecular beam epitaxy(MBE)on sapphire substrates through ion implantation.Krypton is chemically inert.The structures,morphologies,and optical properties of films are measured.The x-ray diffraction(XRD)spectra confirm the wurtzite structures of Zn-polar ZnO films.Atomic force microscopy(AFM)results show that the films have pit surface structure and higher roughness after Kr ion implantation.A detailed investigation of the optical properties is performed by using the absorption spectrum,photoluminescence(PL),and spectroscopic ellipsometry(SE).The absorption spectrum is measured by UV-visible spectrophotometer and the bandgap energy is estimated by the Tauc method.The results show that the absorption increases and the bandgap decreases after Kr ion implantation.Moreover,the Kr ion implantation concentration also affects the properties of the film.The ellipsometry results show that the films'refractive index decreases with the Kr ion implantation concentration increasing.These results can conduce to the design and optimization of Kr ion-implanted polar ZnO films for optoelectronic applications.
基金supported by the National Natural Science Foundation of China (Nos. 12135004, 11635003, 11961141004, and 11875088)
文摘Discussions pertaining to enhancement in the luminous efficiency of cesium iodide(CsI)detectors doped with sodium(Na)abound.In this study,the defect structure of one Cs atom replaced by one Na atom is calculated using the ab initio method.Subsequently,the electronic band structures,densities of states,optical absorption spectra,phonons,and transport properties of CsI in perfect and defective structures are investigated.The absorption spectra of CsI with and without Na impurities are compared.It is discovered that the impurity levels in the forbidden band are generated from the shell electron distributions of the impurity atoms,not from lattice distortions.Furthermore,it is discovered that the optical absorption can be enhanced by doping CsI with Na.
