Screened exciton properties of narrow-gap lead salt finite confining potential semiconductor quantum well

Abstract

A formalism for studying the screened exciton states in the realistic narrow-gap finite confining potential quantum well is developed theoretically with taking into account the quantum well and barrier material parameter's strong contrast across the heteroboundaries. The typical band-nonparabolicity effect of narrow-gap semiconductor has been considered. In the presence of inhomogeneous dielectric polarization of the realistic structure, the suitable in-plane wave vector ranges are established for the average value of the Q2D screened Coulomb potential obtained by Rytova previously. For the two different regimes of Coulomb potential behavior, namely “logarithmical” and “exponential”, the problem of screened exciton binding energy has been investigated variationally at the first time. The analytical and numerical analysis depend on the specifics of realistic narrow-gap EuS/PbS/EuS quantum well are performed. The strong enhancement of the screened exciton binding energy (∼10meV) compared to the tiny unscreened bulk value (∼0.019meV) is received in the presence of the logarithmical potential for thin enough QW, demonstrating that quantum and dielectric confinements together overbalance to the Q2D screening effect. Conversely, in case of exponential potential the binding energy decreases monotonically with the increase of density/ temperature ratio parameter until saturation for the negligible energy values (<1meW). The acceptable intervals of noted ratio parameter in correlation with QW width is also established.