ULTRATHIN GAAS-LAYERS EMBEDDED IN ALAS - A PERSPECTIVE FOR INTENSE SHORT-WAVELENGTH EMISSION

Type-II GaAs/AlAs quantum-well samples grown by low-pressure metal-org anic vapour-phase epitaxy consisting of 50 periods of either 2 monolay ers (ML), 4 ML, 5 ML, 6 ML, or 7 ML GaAs embedded in 28 ML AlAs were u nder investigation. Even at room temperature dominant type-I luminesce nce has been observed. The peak wavelength of this emission ranges fro m 620 to 440 nm and is determined by the GaAs layer thickness. A compa rison of the measured transition energies with model calculations appl ying an effective mass approach and an empirical tight-binding Green's function scheme confirmed this strong dependence. To our knowledge th is is the first report on intense yellow, green, and blue luminescence from GaAs. 1998 Published by Elsevier Science B.V. All rights reserve d.