MOLECULAR-BEAM EPITAXIAL-GROWTH OF HIGH-QUALITY PB1-XSNXTE LAYERS WITH 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1

Lead tin telluride epitaxial layers with tin concentrations covering t he whole compositional range have been grown by molecular beam epitaxy on cleaved BaF2 (1 1 1) substrates, using PbTe and SnTe solid sources . The full width at half maximum of the (2 2 2) rocking curve of these samples, measured by a four crystal high resolution X-ray diffraction apparatus, was about 400 arcsec for the ternary layers, and 150 arcse c for the binary samples. Low temperature Hall mobilities decreased fr om 5 x 10(5) V cm(2)/s, for PbTe, to 2 x 10(3) V cm(2)/s for SnTe, alt hough the crystalline quality is approximately the same. This decrease in mobility is a consequence of the increase in hole concentration fr om 2 x 10(17) cm(-3) to 2 x 10(20) cm(-3), when the Sn concentration c hanges from 0 to 100%. This high carrier concentration in the samples with high Sn content showed a large Burstein-Moss shift in the infrare d transmission spectra measured between 77 and 300 K. (C) 1998 Elsevie r Science B.V. All rights reserved.