Electronic properties of near-surface GaAsrAl Ga As quantum x 1yx wells

Two-dimensional systems such as quantum wells confined on one side by a quasi-infinite barrier and on the other by a very thin variable barrier layer show interesting features. Experimental results show a strong red-shift w1x and, a opposing blue-shift w2x on the transition energy. In order to determine which of the two results is correct, here we study theoretically the electronic properties of near-surface GaAsrGa Al As quantum wells using an empirical Tight-Binding Hamiltonian x 1yx together with the Surface Green Function Matching SGFM.method. We study the effect of the width of the variable barrier on the energy values and the spatial localization of the different states on this heterostructure. q1999 Elsevier Science B.V. All rights reserved