ANALYSIS OF ENERGY-STATES IN MODULATION DOPED MULTIQUANTUM WELL HETEROSTRUCTURES

We present a precise and effective numerical procedure to model the band diagram of modulation doped multiquantum well heterostructures. This method is based on a self-consistent iterative solution of the Schrödinger equation and the Poisson equation. It can be used rather easily in any arbitrary modulation-doped structure. In addition to confined energy subbands, the unconfined states can be calculated as well. Examples on realistic device structures are given to demonstrate capabilities of this procedure. The numerical results are in good agreement with experiments. With the aid of this method we have identified the transitions involving both the confined and unconfined conduction subbands in a modulation doped AlGaAs/GaAs superlattice, and in a strained layer InGaAs/GaAs superlattice. These results represent the first observation of unconfined transitions in modulation doped multiquantum well structures. © 1990.