Optical and structural characteristics of InAs/InGaAs quantum dots-in-a-well (DWELL) heterostructures were investigated. These structures, in which InAs quantum dots are placed in an InGaAs quantum well, which in turn is buried in a GaAs matrix, can be used to realize high performance midinfrared detectors. In this article, we report on the structural and optical properties of these DWELL heterostructures. Five DWELL samples with varying well widths were grown and their properties investigated using transmission electron microscopy (TEM), photoluminescence, normal incidence absorbance, and photocurrent measurement. From the TEM studies, it was observed that, as the InGaAs well thickness increased from 70 to 120 Angstrom, the dots were confined to the upper half of the well. Moreover, a progressive shift was observed in the photocurrent response from 6.7 to 10 mum. Using this approach, a long wave infrared atmospheric window detector was realized. (C) 2004 American Vacuum Society.