Study of growth rate and composition variations in metalorganic vapour phase selective area epitaxy at atmospheric pressure and application to the growth of strained layer DBR lasers

In selective area epitaxy (SAE), a lateral variation of thickness accompanied by a variation of composition occurs because of the presence of dielectric masks on the substrate surface. To take advantage of these behaviours for monolithic integration of electronic devices, a good control of growth rate and composition is necessary. For this aim, different bulk materials InP, InGaAs and InGaAsP have been systematically investigated as a function of the geometry of dielectric masks specially designed for this work. All growths were performed by metalorganic vapour phase epitaxy (MOVPE) at atmospheric pressure. An estimation of growth rate enhancement and composition variation between the open regions in dielectric masks and the unmasked region has been established, allowing the choice of specific mask geometry for each application. Following this study, a strained multiple quantum well (MQW) structure for a distributed Bragg reflector (DBR) laser has been selectively grown. The standard buried ridge structure (BRS) processed presents good characteristics (8 mA threshold current) and we obtained a 7 nm tuning range with a ridge structure, which constitutes the best value reported with SAE.