We report on the use of a novel technique to study reactive ion etching (RIE) induced damage using multiple quantum wens of 20-, 40-, 60-, and 90-A widths as in situ probes. Cathodoluminescence (CL) at low temperature, using a finely focused electron beam, allows sensitive determination of the quality of individual quantum wens before and after RIE damage. There is a correspondence between individual luminescence peaks and the depth of the particular quantum well. We can therefore use the CL spectral information to provide a sensitive profile of the depth of RIE induced damage. Various etching conditions and the effects of postetch anneals are examined. Pure Ar sputtering and enhanced chemical etching using CCI 2 F 2 /BCI 3 at different bias voltages are investigated. Our results reveal that the degree and spatial extent of damage increase with increasing ion energy and decreasing ion mass.

The multiple quantum well (MQW) probe technique has provided information of the depth distribution of dry-etch-induced damage. The observed changes in the quantum well cathodoluminescence intensities or peak positions have been uniquely attributed to the dry etching process. There are indications, however, that this premise may not be justified for some applications. Two studies are described, which we have carried out to establish critical calibrations of the MQW probe technique. A slow, carefully controlled wet etch of the starting MQW probe structure allowed us to observe a reduction in luminescence intensity of quantum wells located less than 20 nm from the surface. The other study reveals that the thicknesses and relative ordering of the quantum wells may influence the interpretation of the MQW data.