PHOTOLUMINESCENCE STUDY OF HGTE-HG0.9CD0.1TE SUPERLATTICES

Infrared photoluminescence (PL) measurements have been performed on 17 [211]-oriented superlattices with energy gaps spanning the range 110- 495 meV. The spectra for 7 different samples display double peaks, whi ch are attributed to monolayer fluctuations in the average thickness o f the quantum wells. The peak splittings vary systematically with PL e nergy gap (E(p)), and are accurately reproduced by orientation-depende nt band structure calculations if the magnitude of the fluctuations is taken to be 1.5 monolayers. These data confirm that the low-temperatu re [211] growth produces islands with monolayer average smoothness ove r lateral dimensions of at least 500-1000 angstrom. Results are compar ed with earlier determinations of the interface roughness correlation length from magneto-transport measurements. In agreement with theoreti cal predictions, the decrease of dE(p)/dT with increasing E(p) is as r apid as that in the Hg1-xCdxTe alloy.