Wavelength tuning of InAs∕InP quantum dots: Control of As∕P surface exchange reaction

Abstract

Wavelength tuning of single and vertically stacked InAs quantum dot (QD) layers embedded in InGaAsP∕InP (100) grown by metal organic vapor-phase epitaxy is achieved by controlling the As∕P surface exchange reaction during InAs deposition. The As∕P exchange reaction is suppressed for decreased QD growth temperature and group V-III flow ratio, reducing the QD size and photoluminescence (PL) emission wavelength. The As∕P exchange reaction and QD PL wavelength are then reproducibly controlled by the thickness of an ultrathin (0–2 ML) GaAs interlayer underneath the QDs. Submonolayer GaAs coverages result in a shape transition from QDs to quantum dashes at low group V-III flow ratio. Temperature dependent PL measurements reveal excellent optical properties of the QDs up to room temperature with PL peak wavelengths in the technologically important 1.55μm region for telecom applications. Widely stacked QD layers are reproduced with identical PL emission to increase the active volume, while closely stacked QD layers reveal a systematic PL redshift and linewidth reduction due to vertical electronic coupling which is proven by the linear polarization of the cleaved-side PL changing from in plane to isotropic.