Growth area control of InAs quantum dots for photonic-crystal-based optical devices by selective MOCVD

Abstract

A technique to control growth area of self-assembled quantum dots is required to avoid optical absorption in fabricating quantum dot lasers with optical passive devices such as photonic crystals in the same growth plane as the active layer. We propose and demonstrate a scheme (Area-Controlled Growth) for controlling growth area of self-assembled InAs quantum dots using selective metalorganic chemical vapor deposition (MOCVD). Using this growth technique, the amount of material deposited within mask windows is controlled by varying the width of the mask. In the growth of self-assembled quantum dots, the density of quantum dots largely depends on the quantities of group III sources used. Therefore, by optimizing the growth conditions and mask pattern, quantum dots can be formed in only selected areas of a growth plane. However, in the regions where dots are formed there is variation of dot density and size along the mask stripe direction because of the diffusion of species in the vapor phase, which is peculiar to selective MOCVD. We achieve more uniform distributions of dot density and size by improving the mask pattern. This growth technique can be also applied to fabricate integrated devices for optical communication system containing an external modulator such as photonic crystals together with quantum dot lasers lasing at 1.3 micrometers .