Composition assessment by spatially resolved photoluminescence of InGaAs and InGaAsP epilayers grown on recessed InP substrates

Epitaxial layers of InGaAs and InGaAsP have been grown on InP recessed substrates by MOVPE. Spatially resolved photoluminescence (PL) at low temperatures has been used to assess the quality of material grown both in the bottom of the recess and on the sidewalls. PL signals from ternary and quaternary epilayers grown on a 100 mu m wide recess both show significant perturbations (10-20 meV) in PL energy at the sidewalls compared with the bulk value. In the middle of the InGaAs recess the lattice-matched PL energy is not re-established, with a blue shift indicating Ga-rich material. For the InGaAsP recess a smaller blue shift in PL energy from the middle of the recess is observed. The effect of growth parameters (reactor pressure and gas flow rate) and the influence of recess width on the perturbation to the PL energy and quality of the InGaAs epilayers described above has also been evaluated.