Type-II superlattices: the Fraunhofer perspective

Abstract

In the past years, the development of the type-II InAs/GaSb superlattice technology at the Fraunhofer-Institute for Applied Solid State Physics (IAF) has been focused on achieving series-production readiness for third generation dualcolor superlattice detector arrays for the mid-wavelength infrared spectral range. The technology is ideally suited for airborne missile threat warning systems, due to its ability of low false alarm remote imaging of hot carbon dioxide signatures on a millisecond time scale. In a multi-wafer molecular beam epitaxy based process eleven 288×384 dualcolor detector arrays are fabricated on 3 GaSb substrates. Very homogeneous detector arrays with an excellent noise equivalent temperature difference have been realized. The current article presents the type-II superlattice dual-color technology developed at IAF and delivers insights into a range of test methodologies employed at various stages during the fabrication process, which ensure that the basic requirements for achieving high detector performance are met.