6. Design and Fabrication of 320 × 256 Focal-Plane Array Using Strain-Coupled Quaternary Capped InAs/GaAs Quantum Dots Infrared Photo-Detectors for Thermal Imaging

We report the fabrication and characterization of a 320 × 256 infrared focal-plane imager fabricated using an strain-coupled quaternary capped InAs quantum dots heterostructure, which showed multiple photoluminescence peak and activation energy of 207.38 meV for dominant peak. Multiple ground state peaks in photoluminescence spectra indicates multimodal dot size distribution which was confirmed using cross-sectional transmission microscopy images. We discuss the fabrication and characterization of single-pixel detectors that can measure intersubband spectral responses with peak intensity at 6.9 µm and narrow spectral linewidth of 19%. The highest detectivity of 2.48 × 10¹⁰ cm Hz^1/2/W at 77 K was observed from proposed structure. Using the fabricated device, infrared images were captured at 50–100 K. Device optimization led to approximately 95% of the pixels in the imaging array being operational and a reasonably low noise equivalent temperature of approximately 0.080 °C at 100 K.