Structural and optical study of InGaAs/InP single layers and multi quantum wells grown under tensile strain condition

Structural and optical studies on single InGaAs layers and InGaAs/InP Multi Quantum Well structures have been performed. The samples were grown with different tensile strain conditions by the MOCVD technique and several conventional and less conventional structural and optical characterization techniques have been used. MQWs have shown inhomogeneous stress relaxation between the crystallographic orientations [1(1) over bar0$] and [110] with cracks crossing the heterostructures only along the [110] direction as observed with Transmission Electron Microscopy and Cathodoluminescence analysis. Reciprocal space maps have revealed this relaxation by the enlargement of the reciprocal lattice points of InP. The strained materials and the partially relaxed materials give the same Photoluminescence signal. The same behavior has been found by Spectral Cathodoluminescence in MQWs at low magnification suggesting that emission in inhomogeneous samples is mainly related to the strained areas.