Electronic properties of near-surface GaAs/AlxGa1-xAs quantum wells

Two-dimensional systems such as quantum wells confined on one side by a qua si-infinite barrier and on the other by a very thin variable barrier layer show interesting features. Experimental results show a strong red-shift [1] and, a opposing blue-shift [2] on the transition energy. In order to deter mine which of the two results is correct, here we study theoretically the e lectronic properties of near-surface GaAs/Ga(x)A(1-x)As quantum wells using an empirical Tight-Binding Hamiltonian together with the Surface Green Fun ction Matching (SGFM) method. We study the effect of the width of the varia ble barrier on the energy values and the spatial localization of the differ ent states on this heterostructure. (C) 1999 Elsevier Science B.V. All righ ts reserved.