Theoretical Study of effect of spatial dielectric function on binding Energy of Donor impurity located on varying pusitions along Z-axis of GaAs quantum well dot of circular cross-section

467-470<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">A theoretical study has been carried out of a donor impurity binding energy in a GaAs/Ga1-x AlxAs Quantum Well Dot (QWD) of circular cross-section and finite length. The derivation of the binding energy was carried out for a potential screened by a dielectric constant, εo, and a spatial dielectric function ε(ρ, z) that varies as the radius and length of the QWD. The donor impurity was placed on varying positions, zi, along the axis of the QWD. A general feature of the results is that in both the dielectric constant and spatial dielectric function regimes, the binding energies were the same at large values of the QWD radius, R, and length, L. However, for smaller radii and length the binding energy in both cases showed marked increase with decreasing QWD radii and length with the binding energy showing a faster increase in the spatial dielectric function regime than in the dielectric constant regime. This feature is seen when the radius is decreased while the length is kept constant and when the length is decreased and the radius is kept constant. The same feature is also seen when the radii and the length are kept constant while the position of the impurity is decreasing towards the origin. These features suggest that in determining the binding energy of a donor impurity in such geometries consideration should be taken of the effect of spatially varying dielectric function.