EVALUATION OF STRAINED INGAAS GAAS QUANTUM-WELLS BY ATOMIC-FORCE MICROSCOPY/

Atomic force microscopy (AFM) is adopted for evaluation of strained In GaAs/GaAs quantum well structures grown by metalorganic vapor phase ep itaxy. InAs-rich clusters are formed at the upper interface when the s tructure is grown with excessive supply of the In precursor. The defec ts arising from the clusters are clearly observed as convex domains fr om the irregularity of monolayer steps. The density of the convex doma ins coincides with the dark spot density measured by cathodoluminescen ce. 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 esti mation of the optical quality of such InGaAs/GaAs structures. (C) 1997 American Institute of Physics.