Figure 11.

Off-center donor impurity related optical absorption coefficient in a cylindrical GaAs-Al_0.3 Ga_0.7 As quantum dot as a function of the incident photon energy and impurity position (axial position-left hand column, radial position-right hand column), with θ = α = π/2 (a–c) and θ = α = 0 (d–f). The results are for F = 50 kV/cm, B = 20 T, R = 20 nm, and H = 20 nm. The vertical red bar at the top indicates the magnitude of the optical absorption coefficient. Note that in order to represent all the results in the same scale, in panel (b) the OAC has been divided. The polarizations of the incident photon are as follows: left hand circular polarized (a,d), right hand circular polarized (b,e), and z-linear polarized (c,f). In all panels, the symbols 0 → n, with n = 1, 2, 3, … (where 0 corresponds to the initial ground state and n is for the final excited one), indicate the allowed optical transitions at z_i = −H/2/x_i = −R (at the bottom of left/right hand panel) and z_i = +H/2/x_i = +R (at the top of left/right hand panel).