InGaAs/GaAsP/AlGaAs, deep-well, quantum-cascade light-emitting structures grown by metalorganic chemical vapor deposition

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) In_0.3Ga_0.7As/Al_0.8Ga_0.2As resonant tunneling diodes (RTDs) were fabricated, which demonstrated high peak-to-valley ratios (∼3) at room temperature (RT) and (2) In_0.3Ga_0.7As/Al_0.7Ga_0.3As 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 °C, high-quality X-ray spectra and RTD action were obtained from the In_0.4Ga_0.6As/Al_0.8Ga_0.2As structures proposed to be used for QC -laser emission in the 4-5 μm range. Narrow-ridge QC structures demonstrated narrow-linewidth electroluminescence spectra indicative of optical gain at 6.7 μm.