InGaAs/GaAs quantum dots on (111)B GaAs substrates

Abstract

InGaAs/GaAs quantum dots have been grown directly on (111) B GaAs substrates using molecular beam epitaxy. The island growth mode, which causes quantum dot formation, is due to the 2X2 surface reconstruction as the growth temperature is lowered. It is not related to the Stranski-Krastanov growth mechanism because the nominal thickness of InGaAs used is far below the critical thickness and no wetting layer is found. Atomic force microscope images indicate island formation with the growth temperature below 480 degrees C. The photoluminescence (PL) spectra of quantum dots show large peak shifts compared with the reference quantum well of the same nominal thickness of InGaAs. The PL emission from the quantum dots is strong and the peaks are narrow. A linewidth as low as 8.5 meV at 8 K has been measured, indicating excellent quality. (C) 1998 American Institute of Physics. [S0021-8979(98)05017-8].