THE COMPOSITION AND STRUCTURE OF INGAAS INALAS INTERFACES AT THE MONATOMIC SCALE/

We have applied high-resolution chemical imaging in a transmission ele ctron microscope to study compositional variations across an InGaAs/In 4lAs double quantum well structure in the (100) orientation. The struc tures of interest are grown on an InP support and consist of two 40 An gstrom layers of InGaAs separated by 20 Angstrom of InAlAs. For this ( InGn)(x)(InAl)(1-x)As system, we have obtained compositional informati on with an accuracy of about 20% and a maximum spatial resolution of 1 /4 unit cell, The results clearly show compositional irregularities on a monatomic scale. (C) 1997 American Institute of Physics.