Photoluminescence and Raman studies of residual stresses in GaAs directly grown on InP

We report first-order Raman spectroscopy and low-temperature photoluminescence (PL) studies of GaAs layers grown by metalorganic vapor phase epitaxy (MOVPE) on InP (100) substrates. From both the shift of the longitudinal-optical phonons in the Raman spectra and the splitting and shift of band-edge exciton lines in PL, the epilayers are found to be under (100) coplanar tensile stress, which is consistent with the difference between the thermoelastic properties of the two materials. The PL analysis shows that carbon is the main residual acceptor impurity in MOVPE-grown GaAs/InP.