HOMOGENEOUS LINEWIDTHS OF EXCITONS IN HIGH AND LOW-BAND-GAP GA0.52IN0.48P

Photoluminescence and picosecond four-wave-mixing experiments are repo rted on Ga0.52In0.48P grown by organometallic vapor phase epitaxy on G aAs substrates. The spectral behavior of the homogeneous linewidth in the range of the inhomogeneously broadened band gap excitonic resonanc e is found to be different for a high band gap as compared to a low ba nd gap structure. Whereas the former shows the normal alloy behavior, the behavior of the low band gap sample supports the assumption that i ts structure consists of ordered domains with varying degrees of order . This means in particular that the main origin of the inhomogeneous b roadening is different for the high and low band gap cases.