Crystal orientation effects on the piezoelectric field of strained zinc-blende quantum-well structures

Acousto-optical phonon excitation in cubic piezoelectric slabs and crystal growth orientation effects

“…It has been shown that the exclusion of anisotropy and the piezoelectric effect leads to significant changes in the phonon dispersion curves for a piezoelectric slab, and that, due to the piezoelectric coupling, certain acoustic phonons are coupled with the electric potential and hence interact with electromagnetic waves, termed acousto-optical phonons [26]. The pronounced effect of anisotropy, however, stipulates that the phonon dispersion relation in a slab also depends on the crystal orientation, just like the electromechanical coupling in general-an effect that already has been studied for other quantum systems, such as quantum-well structures where the lattice-mismatch induced strain causes electric fields in the well region, highly influential for LED applications [27,28].…”

Electromechanical Fields in Quantum Heterostructures and Superlattices

“…a periodic repetition of well and barriers) are exactly the same, with the lattice constants in the well layers adapting to those of the barrier (Poccia et al, 2010). Calculations for the [111] growth direction of zincblende crystals yields the following analytical expression for the compressional strain in the quantum well (Duggen et al, 2008): Caridi et al (1990) b J.I. Izpura et al (1999) It can be seen that it does not play a role whether one uses the fully-coupled or the semi coupled approach for the nitrides.…”

“…The cubes to the left indicate the cubic crystal structure while the middle and right figures represent the same operation for hexagonal crystals. Reprinted with permission from Duggen et al (2008) and Duggen & Willatzen (2010).…”

“…It is seen that the transversely dominated resonances (only at [111] the, at this direction degenerate, transverse polarizations are uncoupled from the compressional one) are much lower than the compressionally dominated ones, as one would expect. Thus, when computing resonance frequencies it is important not to compute the ideal [111] direction only, but also take into account the significantly lower frequencies as they might occur due to lattice imperfections (Duggen et al, 2008). …”

Heteroepitaxy of III–V Zinc Blende Semiconductors on Nanopatterned Substrates

“…A particular advantage of zinc blende semiconductors as opposed to their wurtzite-structure counterparts is that piezoelectric fields occur to a much lesser extent in the former because of their high symmetry. In zinc blende layers grown along the [001] direction piezoelectric effects are completely absent [5].…”