The hydrogenic donor impurity states and intersubband optical absorption spectra in monolayer transition metal dichalcogenides(ML TMDs) under dielectric environments are theoretically investigated based on a two-dimen...The hydrogenic donor impurity states and intersubband optical absorption spectra in monolayer transition metal dichalcogenides(ML TMDs) under dielectric environments are theoretically investigated based on a two-dimensional(2D)nonorthogonal associated Laguerre basis set. The 2D quantum confinement effect together with the strongly reduced dielectric screening results in the strong attractive Coulomb potential between electron and donor ion, with exceptionally large impurity binding energy and huge intersubband oscillator strength. These lead to the strong interaction of the electron with light in a 2D regime. The intersubband optical absorption spectra exhibit strong absorption lines of the non-hydrogenic Rydberg series in the mid-infrared range of light. The strength of the Coulomb potential can be controlled by changing the dielectric environment. The electron affinity difference leads to charge transfer between ML TMD and the dielectric environment, generating the polarization-electric field in ML TMD accompanied by weakening the Coulomb interaction strength. The larger the dielectric constant of the dielectric environment, the more the charge transfer is, accompanied by the larger polarization-electric field and the stronger dielectric screening. The dielectric environment is shown to provide an efficient tool to tune the wavelength and output of the mid-infrared intersubband devices based on ML TMDs.展开更多
研究了 Al Ga As层掺 1%的 In对 Al Ga As/Ga As量子阱光致发光谱的半峰宽的影响 .2 5 K的光致发光结果表明 ,In作为表面活化剂能有效改善 Al Ga As/Ga As异质界面的粗糙度 .将此方法应用到反型 Al Ga As/Ga As高电子迁移率晶体管 (HEMT...研究了 Al Ga As层掺 1%的 In对 Al Ga As/Ga As量子阱光致发光谱的半峰宽的影响 .2 5 K的光致发光结果表明 ,In作为表面活化剂能有效改善 Al Ga As/Ga As异质界面的粗糙度 .将此方法应用到反型 Al Ga As/Ga As高电子迁移率晶体管 (HEMT)材料结构中 ,Hall测量表明该方法能有效提高反型展开更多
The exciton Stark shift and polarization in hemispherical quantum dots(HQDs)each as a function of strength and orientation of applied electric field are theoretically investigated by an exact diagonalization method.A ...The exciton Stark shift and polarization in hemispherical quantum dots(HQDs)each as a function of strength and orientation of applied electric field are theoretically investigated by an exact diagonalization method.A highly anisotropic Stark redshift of exciton energy is found.As the electric field is rotated from Voigt to Faraday geometry,the redshift of exciton energy monotonically decreases.This is because the asymmetric geometric shape of the hemispherical quantum dot restrains the displacement of the wave function to the higher orbital state in response to electric field along Faraday geometry.A redshift of hole energy is found all the time while a transition of electron energy from this redshift to a blueshift is found as the field is rotated from Voigt to Faraday geometry.Taking advantage of the diminishing of Stark effect along Faraday geometry,the hemispherical shapes can be used to improve significantly the radiative recombination efficiency of the polar optoelectronic devices if the strong internal polarized electric field is along Faraday geometry.展开更多
文摘The hydrogenic donor impurity states and intersubband optical absorption spectra in monolayer transition metal dichalcogenides(ML TMDs) under dielectric environments are theoretically investigated based on a two-dimensional(2D)nonorthogonal associated Laguerre basis set. The 2D quantum confinement effect together with the strongly reduced dielectric screening results in the strong attractive Coulomb potential between electron and donor ion, with exceptionally large impurity binding energy and huge intersubband oscillator strength. These lead to the strong interaction of the electron with light in a 2D regime. The intersubband optical absorption spectra exhibit strong absorption lines of the non-hydrogenic Rydberg series in the mid-infrared range of light. The strength of the Coulomb potential can be controlled by changing the dielectric environment. The electron affinity difference leads to charge transfer between ML TMD and the dielectric environment, generating the polarization-electric field in ML TMD accompanied by weakening the Coulomb interaction strength. The larger the dielectric constant of the dielectric environment, the more the charge transfer is, accompanied by the larger polarization-electric field and the stronger dielectric screening. The dielectric environment is shown to provide an efficient tool to tune the wavelength and output of the mid-infrared intersubband devices based on ML TMDs.
文摘研究了 Al Ga As层掺 1%的 In对 Al Ga As/Ga As量子阱光致发光谱的半峰宽的影响 .2 5 K的光致发光结果表明 ,In作为表面活化剂能有效改善 Al Ga As/Ga As异质界面的粗糙度 .将此方法应用到反型 Al Ga As/Ga As高电子迁移率晶体管 (HEMT)材料结构中 ,Hall测量表明该方法能有效提高反型
文摘The exciton Stark shift and polarization in hemispherical quantum dots(HQDs)each as a function of strength and orientation of applied electric field are theoretically investigated by an exact diagonalization method.A highly anisotropic Stark redshift of exciton energy is found.As the electric field is rotated from Voigt to Faraday geometry,the redshift of exciton energy monotonically decreases.This is because the asymmetric geometric shape of the hemispherical quantum dot restrains the displacement of the wave function to the higher orbital state in response to electric field along Faraday geometry.A redshift of hole energy is found all the time while a transition of electron energy from this redshift to a blueshift is found as the field is rotated from Voigt to Faraday geometry.Taking advantage of the diminishing of Stark effect along Faraday geometry,the hemispherical shapes can be used to improve significantly the radiative recombination efficiency of the polar optoelectronic devices if the strong internal polarized electric field is along Faraday geometry.
