Piezoelectric-field effect on electronic and optical properties of [111] In_xGa_1-xAs/GaAs superlattices

We theoretically analyze effects of the piezoelectric field and its screening on the electronic and optical properties including optical matrix element and spontaneous emission for In_xGa_1-xAs/GaAs superlattices (SLs). For the investigation we take [111] In_0.15Ga_0.85As/GaAs SL with three types of structures according to well/barrier widths of 40 Å/40 Å, 100 Å/100 Å, and 160 Å/160 Å. The carrier densities are assumed to be equivalent to 5×10¹⁶, 1×10¹⁷, 5×10¹⁷, 1×10¹⁸, and 5×10¹⁸ cm^-3 over 40 Å width in the wells. In the numerical computations, 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-consistently solves 8×8 (conduction, heavy, light, and spin split-off valence bands) effective-mass Schrödinger equation and the Hartree and exchange-correlation potential equations through the variational procedure. The results show that piezoelectric field causes significant changes in the electronic and optical properties; however, the screening of piezoelectric field by the carriers in the wells seems not very effective for device application. © 2001 American Institute of Physics.