Type-II superlattice infrared detector technology at Fraunhofer IAF

Abstract

For more than two decades, Antimony-based type-II superlattice photodetectors for the infrared spectral range between 3-15 μm are under development at the Fraunhofer Institute for Applied Solid State Physics (IAF). Today, Fraunhofer IAF is Germany’s only national foundry for InAs/GaSb type-II superlattice detectors and we cover a wide range of aspects from basic materials research to small series production in this field. We develop single-element photodetectors for sensing systems as well as two-dimensional detector arrays for high-performance imaging and threat warning systems in the mid-wavelength and long-wavelength region of the thermal infrared. We continuously enhance our production capabilities by extending our in-line process control facilities. As a recent example, we present a semiautomatic wafer probe station that has developed into an important tool for electrooptical characterization. A large amount of the basic materials research focuses on the reduction of the dark current by the development of bandgap engineered device designs on the basis of heterojunction concepts. Recently, we have successfully demonstrated Europe’s first LWIR InAs/GaSb type-II superlattice imager with 640x512 pixels with 15 μm pitch. The demonstrator camera already delivers a good image quality and achieves a thermal resolution better than 30 mK.