p-type delta-doping quantum wells and superlattices in Si: Self-consistenthole potentials and band structures

The hole-subband and -miniband structures of periodically acceptor delta-do ped quantum wells and superlattices (SL's) in silicon are calculated self-c onsistently within the effective-mass theory and the local-density approxim ation. The full six-band Luttinger-Kohn effective-mass equations are solved , together with Poisson equation, in a plane-wave representation. Nonparabo licities due to couplings between heavy, light, and spinorbit split bands a re fully taken into consideration. To account for exchange and correlation (XC) effects within the multicomponent hole gas, a parametrized expression for the XC potential energy is adopted. Hole band structures, Fermi levels, and potentials are presented for a series of p-type delta-doping SL's, var ying the acceptor doping concentrations, periods, and doping spreads. The i nclusion of the spin-orbit split band is reflected essentially in nonparabo licities, and it starts to play an important role already for intermediate concentrations. For acceptor doping concentrations above 1.1X10(14) cm(-2), the split-off band is populated for SL periods in both SL and isolated wel l regimes. A comparison with the available experimental data shows fairly g ood agreement. Particularly, the data reported on admittance and infrared s pectroscopies can be reasonably interpreted if one assumes indirect transit ions between subbands, as is the case in p-type delta-doped GaAs. [S0163-18 29(98)00747-4].