Self-assembled InAs quantum dots (QD) over an InP, InGaAs, InGaAlAs on InP substrates were grown by metal-organic chemical vapor deposition (MOCVD) and were investigated for quantum dot infrared photodetectors. For InAs QD over an InP buffer on different InP substrates. The results indicate that the presence of dislocations were responsible for the increase in the QD density. Photoluminescence (PL) spectra of InP/InxGa1-xAs/InAs/InP dot-in-a-well structures, with different compositions of the ternary layer. Measurements with atomic force microscopy showed that the largest QD height is obtained when the InAs QDs are grown on the InxGa1-xAs layer with a mismatch of 1000ppm, and the height decreases as the mismatch departs from this value. PL spectra of the QDs showed an asymmetric band, which involves transitions between dot energy levels and can be deconvoluted into two peaks. The highest energy PL peak of this band was observed for the sample with the QDs grown on top of the lattice-matched InxGa1-xAs and it shifted to lower energies for strained samples as the degree of mismatch increased. Different InAs quantum dot structures grown on InGaAlAs lattice matched to InP. Extremely narrow photocurrent peaks were observed, demonstrating great potential for fine wavelenght selection. Structures which can detect radiation beyond 10ìm were developed. Polarization dependence measurements showed that the structures have a zero- dimensional character and are suitable for detection of normal incidence light.