Liquid phase epitaxial growth of six-layer GaAs/(GaAl)As structures for injection lasers with 0.04 μm thick centre layer

Abstract

Multilayer liquid phase epitaxy of GaAs and (GaAl)As from Ga solution, using a rotary graphite crucible in a vertical furnace, has been developed so that GaAs layers down to less than 0.04 μm thickness and (GaAl)As layers down to less than 0.08 μm thickness can be grown reproducibly on GaAs substrates. Five layer (+ contacting layer) localised gain injection lasers made from these slices give very consistent performance. During growth reasonable equilibrium is maintained in the melts, cooled at 0.2 °C/min, by allowing solid to float on the top at the growth temperature. The small supersaturation which remains is counteracted by a vertical temperature gradient of about 2.5°C/cm (slice hotter than solution). Analysis shows that the solute transport in the growth of (GaAl)As is by diffusion, but that a more rapid process occurs in the growth of GaAs, possibly constitutional convection.