InAs/(GaIn)Sb short-period superlattices for focal plane arrays
Kurzperiodige InAs/(GaIn)Sb Übergitter für Bildfeldmatrizen
An infrared camera based on a 256x256 focal plane array for the Mid-IR spectral range (3-5 mu m) has been realized for the first time with InAs/GaSb short-period superlattices. The detector shows a cut-off wavelength of 5.4 mu m and reveals a quantum efficiency of 30%. The noise equivalent temperature difference (NETD) reaches 9.4 mK at 73 K with F/2 optics and 6.5 ms integration time. Excellent thermal images with low NETD values and a very good modulation transfer function are presented. Furthermore, a new method to passivate InAs/GaInSb superlattice photodiodes for the 8-10 mu m regime is demonstrated. The approach is based on the epitaxial overgrowth of wet-etched mesa diodes using lattice matched AlGaAsSb. A complete suppression of surface leakage currents in small sized test diodes with 70 mu m diameter is observed.