DESIGN AND CHARACTERISTICS OF HIGH PERFORMANCE LONG WAVELENGTH TYPE-2 SUPERLATTICE SENSORS

Date

2024-1-22

Author

Oğuz, Fikri

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Type-2 Superlattices (T2SLs) show great prospects for future infrared operations ranging from military to daily based applications due to their high-performance promises. Even if they include complex theoretical considerations not only for structural design but also for growth mechanisms, they offer flexibility to tune conditions according to the target performance parameters. Starting from the 2010s, high-performance Type-2 Superlattice sensors were fabricated, and many countries focused on obtaining technology and improving existing capabilities. Qualified detectors and thermal cameras are now available in the market in both the mid-wavelength infrared region (MWIR) and long-wavelength infrared region (LWIR). However, due to the smaller bandgap in LWIR, the growth and fabrication of LWIR T2SLs are still significant topics to be developed. In the thesis, LWIR InAs/GaSb Type-2 Superlattices are investigated in terms of design considerations, fabrication, and characterization. Two different LWIR T2SL epilayers were designed, and their electro-optical performances were compared at both large-sized test detectors and Focal Plane Array levels. 640x512 format with a 15 μm pixel pitch was implemented for FPAs. Different production approaches were tried to achieve ultimate performance regarding dark current, responsivity, Noise Equivalent Temperature Difference (NETD), and operability. The large area diodes from the 9.3 μm-cut-off-epilayer yielded 1x10^-3 A/cm^2 dark current densities, while FPAs that hybridized with ROIC showed 45 mK NETD with f/2.0 optics and 92% operability. The acquired images and diode characterization results from both epilayer designs will be provided.

Subject Keywords

Type-2 Superlattice, Infrared Photodetectors, Long Wavelength Infrared Region, LWIR, Focal Plane Array

URI

https://hdl.handle.net/11511/108497

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Graduate School of Natural and Applied Sciences, Thesis