First-step nucleation growth dependence of InAs/InGaAs/InP quantum dot formation in two-step growth

First-step nucleation growth has an important impact on the two-step growth of high-quality mid-infrared emissive InAs/InGaAs/InP quantum dots (QDs). It has been found that an optimized growth rate for first-step nucleation is critical for forming QDs with narrow size distribution, high dot density and high crystal quality. High growth temperature has an advantage in removing defects in the QDs formed, but the dot density will be reduced. Contrasting behavior in forming InAs QDs using metal-organic vapor phase epitaxy (MOVPE) by varying the input flux ratio of group-V versus group-III source (V/III ratio) in the first-step nucleation growth has been observed and investigated. High-density, 2.5 x 10(10) cm(-2), InAs QDs emitting at > 2.15 mu m have been formed with narrow size distribution, similar to 1 nm standard deviation, by reducing the V/III ratio to zero in first-step nucleation growth.