Non-destructive optical characterization of the surface region in bulk semiconductors and heterostructures

This paper describes application of picosecond non-degenerate four-wave mixing spectroscopy for the characterization of the surface region in layered semiconductor heterostructures. To demonstrate the influence of decreasing dimensionality of a structure on the experimental results, three model systems with progressively decreasing average layer thickness l(z): bulk GaAs (l(z) --> infinity), CdTe/ZnTe heterostructure (l(z) approximate to 1 mu m), and GaAs/InGaAs MQW structure (l(z) approximate to 10 nm) were characterized by non-degenerate four-wave mixing. Analysis of the obtained data demonstrates important aspects related to application of this technique for the characterization of thin films and low-dimensional structures. (C) 2000 Elsevier Science S.A. All rights reserved.