Abstract:Polarization resolved photoluminescence from a cleaved sample edge (edge photoluminescence) was used to investigate the valence-band splitting in GaNAs/GaAs single quantum wells. The spectra resulting from the heavy- and light-hole transitions shows an interesting phenomenon, in which the light-hole state is above the heavy-hole state at low temperatures, they degenerate at about 195 K, and finally the light-hole state is below the heavy-hole state at higher temperatures. We point out that the underlying origin of our observation can be attributed to the competitive effect between the tensile strain induced by lattice mismatch and quantum confinement. It is known that the large density of heavy-hole states is beneficial for laser diodes. Our result is therefore very useful for the application of GaNAs/GaAs quantum wells in optical devices.