OPTIMIZATION OF SELECTIVE-AREA EPITAXY FOR FABRICATION OF CIRCULAR GRATING DISTRIBUTED-BRAGG-REFLECTOR SURFACE-EMITTING LASERS

The factors affecting the quality of regrowth of semi-insulating lambda = 1.1 mum InGaAsP around circular mesas for the fabrication of circular grating distributed-Bragg-reflector surface-emitting lasers were investigated. Reactive ion etching of the mesas avoids the exposure of no growth planes on the mesa sidewalls, which results in good regrowth morphology around the entire mesa at a growth pressure of 50 mbar. High resolution scanning photoluminescence of the regrown quaternary material reveals a minimal 4 nm wavelength shift to longer wavelengths as the mesa edge is approached. A map of the photoluminescence intensity indicates that the quality of the regrown material is uniform around the periphery of the mesas. Fe doping of lambda = 1.1 mum InGaAsP increases linearly with reactor gas pressure for fixed dopant and total gas flows, so the dopant flow must be adjusted for regrowth at a different reactor pressure if the same doping is desired. Activation of Fe in lambda = 1.1 mum InGaAsP is independent of hydride concentration in the reactor in the range of (2-9) x 10(-5) mol/l, and is virtually complete.