Very long wavelength infrared focal plane arrays with 50% cutoff wavelength based on type-II InAs/GaSb superlattice**Project supported by the National Basic Research Program of China (Grant Nos. 2013CB932904 and 2011CB922201), the National Special Funds for the Development of Major Research Equipment and Instruments, China (Grant No. 2012YQ140005), and the National Natural Science Foundation of China (Grant Nos. 61274013, 61290303, and

Abstract

A very long wavelength infrared(VLWIR) focal plane array based on InAs/GaSb type-II super-lattices is demonstrated on a GaSb substrate. A hetero-structure photodiode was grown with a 50% cut-off wavelength of 15.2 m, at 77 K. A 320×256 VLWIR focal plane array with this design was fabricated and characterized. The peak quantum efficiency without an antireflective coating was 25.74% at the reverse bias voltage of −20 mV, yielding a peak specific detectivity of cm·Hz ·W−1. The operability and the uniformity of response were 89% and 83.17%. The noise-equivalent temperature difference at 65 K exhibited a minimum at 21.4 mK, corresponding to an average value of 56.3 mK.