Metasurface-coupled superlattices for LWIR imaging

Sivananthan Laboratories, Inc. with the University of Iowa proposes two major improvements to superlattice (SL) detector technology which are predicated to enhance the LWIR imaging performance comparable or better than HgCdTe-based detector performance. The performance of the current SL detectors is limited by the prevalence of native point defects (NPDs), thicker SL absorber region as required by poor SL absorption coefficient, and shorter diffusion time owing to smaller mobility in growth direction. The detector design with reduced NPDs in SL and increased absorption in smaller absorption volume will address these issues. With inherently suppressed Auger recombination in SL structures, these improved SL designs will compete more favorably against HgCdTe detectors. We propose to employ a combination of first-principles Hamiltonians for defect potentials, wavefunctions from tight-binding Hamiltonian, and Green’s functions to calculate the defect energy levels and formation energies of 14 different NPDs in SL and a select a design without any, or mid-gap, states from the NPDs. In Phase I, we will extend our calculations to include interstitials to identify an NPD-free SL design and demonstrate high absorption in SL with our designed metasurface. The issues related to FPA array development and ROIC integration will be identified for demonstration in Phase II. Approved for Public Release | 21-MDA-11013 (19 Nov 21)