Properties Of Ionized-donor-bound Excitons Near A Semiconductor-metal Interface

The semiconductor material is one of the most important materials in our society. Humanproduction and life has also been made with semiconductor devices in a very wide range ofapplications. It is well known that the electrical and optical properties of bulk and lowdimensional semiconductors strongly depend on the presence of donor impurities. Recentlythere has been an enhanced interest to study shallow donor impurities near an interfacebecause of its importance in atomic scale electronics and nanoelectronics.In this paper, we use a variational approach to study the properties of theionized-donor-bound excitons near a semiconductor/metal interface. We use the model of acylindrical coordinate system, by constructing a trial wave function of the ground-state energyof the system, the binding energy and the average value of the each particle position in ρdirection versus the donor position in units ofa Bfor the semiconductor/metal interface,and the results are discussed in detail.First of all, the calculated results show that the binding energy of theionized-donor-bound excitons near a semiconductor/metal interface decreases as the distancebetween the donor and the interface increases, because of the image charge. Without theimage charges, the ground state energy tends to steady and approaches the bulk result frombelow for d�'∞.And then, the binding energies of the ionized-donor-bound excitons in two differentdissociation processes are calculated and are compared with each other. The relation betweenboth of them is analysed intensively in this paper.Finally, the average value of the electron and the hole position in ρ direction areinvestigated as a function of the donor position in units ofa Busing the ground-state wavefunction, and the satisfactory results are obtained.