The effects of close packing and electric fields on the optical properties of three-dimensionally stacked quantum dots

摘要

An algorithm to evaluate the position of spherical quantum dots in a closely packed state inside a cube is presented and its accuracy confirmed numerically. A finite-difference method to solve the corresponding three-dimensional Schrodinger equation in the presence of an external electric field is then described. The Arnoldi factorization method is used to diagonalize the resulting huge sparse matrix. The results reveal that both the intensity and direction of the electric field can significantly change the height of the absorption peak and are thus both important. Two different semiconducting structures, viz. GaAs/AlxGa1-xAs and InSb/GaSb, are investigated, revealing that the latter exhibits a more tunable absorption coefficient. The effect of the composition parameter x on the mentioned optical properties is also studied. The combination of this and earlier work indicates that photodetection in the wide range of 1.2-8.4 THz is possible. The proposed structure can thus be regarded as a possible candidate for use in photodetection devices in different fields of industries such as imaging, medicine, and materials characterization.