Growth and optical properties of (112)BHgTe/Hg1-xCdxTe superlattices

The molecular beam epitaxial growth and the optical properties of (1 1 2) B oriented HgTe/Hg1-xCdxTe superlattices (SLs) are compared with those of (0 0 1) orientated SLs. First of all, the Hg1-xCdxTe barriers have a much higher Cd concentration than those in (0 0 1) grown under similar conditions, i.e. x = 0.95 +/- 0.02 as opposed to x = 0.68 +/- 0.02 at a growth temperature of 180 degrees C. In addition the optical absorption edges are appreciably sharper than those in (0 0 1) oriented SLs grown under similar conditions, by a factor of at least two. Analogously, the full-width at half-maximum of the photoluminescence (PL) peak, e.g. 8 meV for a band gap of 100 meV at 4 K, is at least a factor of two narrower than that in our best (0 0 1) oriented SLs. This can be explained by a more homogeneous growth laterally, i.e. in the plane perpendicular to the growth direction: either more homogeneous quantum well and barrier thicknesses or a more homogeneous interface width. (C) 1998 Elsevier Science B.V. All rights reserved.