Self-organized InAs islands on InP(311)B substrates emitting around 1.55 mu m

The influence of the InP(3 1 1)B high index substrate on InAs island charac teristics, is investigated as regards to the (1 0 0) substrate. The AFA? im ages of a nominally 2.1 ML thick InAs layer show that the island density is 10 times higher on the (3 1 1)B substrate than on (1 0 0). The average isl and diameter and height on (3 1 1)B are half the average values on (1 0 0). Careful observations of the island profiles on AFM images allow to determi ne facets close to low index crystallographic planes. The islands grown on the (3 1 1)B surface lead to a steady photoluminescence emission at 0.7 eV for a wide range of InAs growth conditions. Ln order to tune this PL emissi on wavelength around 1.55 mu m (0.8 eV), the islands have been exposed unde r a phosphorous overpressure for various times up to 20 s before bring capp ed with the InP layer. The As/P exchanges induce a blue shift of the PL emi ssion up to 250 meV. (C) 1999 Elsevier Science B.V. All rights reserved.