THOMAS-FERMI APPROXIMATION IN A TIGHT-BINDING CALCULATION OF DELTA-DOPED QUANTUM-WELLS IN GAAS

We present a tight-binding calculation of the electronic structure of delta-doped quantum wells in GaAs. A self-consistent potential obtaine d in the Thomas-Fermi approximation is considered as an external poten tial in our tight-binding model. A spin-dependent sp(3)s basis is use d and nearest neighbors are considered to treat GaAs bulk crystals dop ed with Si or Be. We change the semiempirical Hamiltonian matrix of th e (001) direction in each atomic layer, adding the value of the self-c onsistent external potential in this layer to all diagonal elements of the matrix. The inhomogeneous delta-doped finite region is matched wi th two semi-infinite homogeneous GaAs barriers within the framework of the surface Green-function matching method. We compare the tight-bind ing results with the results obtained in the envelope-function approxi mation and with the experimental data available for the Si- and Be-dop ed GaAs. [S0163-1829(98)04323-9].