Evaluation of strained InGaAs/GaAs quantum wells by atomic force microscopy

Atomic force microscopy (AFM) is adopted for evaluation of strained InGaAs/GaAs quantum well structures grown by metalorganic vapor phase epitaxy. InAs-rich clusters are formed at the upper interface when the structure is grown with excessive supply of the In precursor. The defects arising from the clusters are clearly observed as convex domains from the irregularity of monolayer steps. The density of the convex domains coincides with the dark spot density measured by cathodoluminescence. Photoluminescence intensity is drastically reduced at high density of this type of defects. Thus, AFM measurements are able not only to give information on the structural quality but also to provide an estimation of the optical quality of such InGaAs/GaAs structures. (C) 1997 American Institute of Physics.