InGaAs/GaAsP/AlGaAs strain-compensated, deep-well quantum-cascade (QC) structures have been grown by low-pressure metalorganic chemical vapor deposition (MOCVD). The structures were evaluated by high-resolution X-ray diffraction (HRXRD), transmission electron microscopy (TEM), and fabricated into narrow-ridge QC light emitters for electroluminescence characterization. The HRXRD patterns and cross-sectional TEM images show that well-controlled InGaAs/GaAsP/AlGaAs QC structures can be achieved via MOCVD growth. To characterize highly strained InGaAs quantum wells (QWs) two approaches were taken: (1) In0.3Ga0.7As/Al0.8Ga0.2As resonant tunneling diodes (RTDs) were fabricated, which demonstrated high peak-to-valley ratios (similar to 3) at room temperature (RT) and (2) In0.3Ga0.7As/Al0.7Ga0.3As QW infrared (IR) absorption samples were designed and grown, which, demonstrated narrow (24 meV full-width at half-maximum-(FWHM)) absorption spectra at RT. By lowering the growth temperature to 580 degrees C, high-quality X-ray spectra and RTD action were obtained from the In0.4Ga0.6As/Al0.8Ga0.2As structures proposed to be used for QC -laser emission in the 4-5 mu m range. Narrow-ridge QC structures demonstrated narrow-linewidth electroluminescence spectra indicative of optical gain at 6.7 mu m. (C) 2008 Elsevier B.V. All rights reserved.