LATTICE STRAIN RELAXATION IN GAAS INP(001) AND GAAS/GAP(001) HETEROSTRUCTURES/

GaAs/InP and GaAs/GaP heterostructures have lattice mismatches with ne arly the same absolute value but opposite sign; therefore, they are id eal candidates for investigating the role of the strain sign on the st rain relaxation mechanisms. (001) oriented GaAs/InP and GaAs/GaP heter ostructures have been grown by metallorganic vapour phase epitaxy and the strain release has been studied by high resolution X-ray diffracti on. The residual strain parallel to the interface has been determined as a function of the layer thickness for both the systems and the resu lts compared with the theoretical predictions of the equilibrium model . The present findings, together with those previously obtained in InP /GaAs structures grown by atomic layer epitaxy, allowed some general c onclusions on the strain relaxation mechanisms to be achieved.