TEM CHARACTERIZATION OF THE INTERFACE QUALITY OF MOVPE GROWN STRAINED INGAAS/GAAS HETEROSTRUCTURES

In order to optimize the growth conditions of strained-layer InGaAs QW high-performance lasers by MOVPE, different growth parameters are systematically varied. These test structures as well as complete laser structures are carefully analysed. Special attention is given among others to the homogeneity and interface quality of the quantum well. For ''thicker'' QW layers (>7 nm) - grown under standard conditions - it is possible to prove an increased smearing of the upper QW interface. This observation is in good correlation with AES measurements. For the first time, the inhomogeneous In distribution in the QW could be visualized as a detectable segregation of In in the interface region by using high-resolution TEM techniques and new methods of image analysis.