Piezoelectric-field effect on electronic and optical properties of [111] InxGa1-xAs/GaAs superlattices

We theoretically analyze effects of the piezoelectric field and its screeni ng on the electronic and optical properties including optical matrix elemen t and spontaneous emission for InxGa1-xAs/GaAs superlattices (SLs). For the investigation we take [111] In0.15Ga0.85As/GaAs SL with three types of str uctures according to well/barrier widths of 40 Angstrom /40 Angstrom, 100 A ngstrom /100 Angstrom, and 160 Angstrom /160 Angstrom. The carrier densitie s are assumed to be equivalent to 5x10(16), 1x10(17), 5x10(17), 1x10(18), a nd 5x10(18) cm(-3) over 40 Angstrom width in the wells. In the numerical co mputations, we use the computation model presented recently by [B. W. Kim, J. H. Yoo, and S. H. Kim, ETRI Journal 21, 65 (1999)]. The model self-consi stently solves 8x8 (conduction, heavy, light, and spin split-off valence ba nds) effective-mass Schrodinger equation and the Hartree and exchange-corre lation potential equations through the variational procedure. The results s how that piezoelectric field causes significant changes in the electronic a nd optical properties; however, the screening of piezoelectric field by the carriers in the wells seems not very effective for device application. (C) 2001 American Institute of Physics.