Self-organized InAs islands on InP(3 1 1)B substrates emitting around 1.55 μm

Abstract

The influence of the InP(3 1 1)B high index substrate on InAs island characteristics, is investigated as regards to the (1 0 0) substrate. The AFM images 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 island 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 determine 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. In order to tune this PL emission wavelength around 1.55 μm (0.8 eV), the islands have been exposed under a phosphorous overpressure for various times up to 20 s before being capped with the InP layer. The As/P exchanges induce a blue shift of the PL emission up to 250 meV.