Wave packets in a semiconductor superlattice

When a short laser pulse excites a quantum system, a spatially localized wave packet is formed.1 In this paper, we present a theoretical study of hole wave packets in a room temperature semiconductor superlattice, the unit cell of which consists of four layers. The first and third layers are GaAs wells of width 9 and 14 monolayers, 25.4 and 39.6 A. The second and fourth are 5 monolayers, 14.1-Å thick Al0.3Ga0.7As barriers. Effectively, the material is a series of coupled quantum wells of alternating thicknesses. These parameters give an even splitting between the first three hole states. The bandgap discontinuity is split, with 43% allotted to the valence band, and the growth direction is 100. The theoretical model is a k.p. local pseudopotential method based on that of Smith and Mailhiot.2