Photoluminescence and TEM characterization of (Al_yGa_1–y)_1–xIn_xP layers grown on graded buffers

Abstract

Composition, crystallographic quality and low temperature photoluminescence of AlGaInP quaternary layers were studied. These layers were grown on the InGaP/GaP graded buffers by metalorganic vapour phase epitaxy. Final composition of the graded buffer top layer was x In = 0.24. Incorporation of the small amount Al into quaternary led to a substantial improvement of the surface morpohology and crystallographic quality observed in cross-sectional TEM view. Incorporation of higher amount of Al (above 1% ) led to the increase of lattice mismatch, decrease of In content in the alloy and to the indirect band gap.