Growth interruption to tune the emission of InAs quantum dots embedded in InGaAs matrix in the long wavelength region

We investigate the effects of combining growth interruption (GI) and InGaAs strain reducing matrix at low In content on the optical properties of Stanski-Krastanow InAs QDs grown by molecular beam epitaxy. Atomic force microscopy and Photoluminescence (PL) measurements were carried out on three series of uncapped and capped samples grown in different conditions: (a) low arsenic pressure (As BEP=4×10-6 Torr) and relatively low InAs growth temperature (TInAs=530°C); (b) low As BEP (4×10-6 Torr) and high TInAs (545°C); (c) high As BEP (7×10-6 Torr) and low TInAs (530°C). Our studies clearly show that in the three growth regimes, GI causes very different effects on the morphological and optical properties of InAs QDs embedded in InGaAs matrix (In=0.12), ruled by the In diffusion and desorption processes. In particular, for samples grown at 530°C and As BeP=4×10-6 Torr (series a), the arrangment of GI and QD embedding in an InGaAs matrix at low In content is an effcient method to tune the InAs QD PL emission and to improve their optical quality. In this case, indeed, the increase of the interruption time up to 300 s introduces a strong redshift (~110 meV) in the PL peak with a decreasing of the linewidths from 52 to 26 meV, obtaining room temperature emission characterized by a narrow peak close to 1.3 ?m.