Published online by Cambridge University Press: 26 February 2011
The capability of growing high quality strained-layer superlattices (SLS's) from lattice-mismatched semiconductors opens up new opportunities in both basic and applied material sciences. This flexibility in the choice of SLS layer materials allows the study of quantum well effects in a variety of new and interesting heterojunction systems. In addition, the large tetragonal distortions of the SLS layers allow these structures to exhibit unique features which are not found in bulk semiconductors. An exciting example is the possibility of tailoring certain SLS materials so that they exhibit small two dimensional hole effective masses and enhanced low field hole mobilities at low temperatures and low carrier concentrations. Band structure calculations indicate that the layer strains, the direct band gap magnitudes of the layers, the valence band offset, and the hole energies all can play a role in determing these small two dimensional hole effective mass values.