Proceedings Article | 16 May 2017
Proc. SPIE. 10177, Infrared Technology and Applications XLIII
KEYWORDS: Infrared detectors, Semiconductors, Mid-IR, Photodetectors, Indium arsenide, Sensors, Diffusion, Doping, Gallium antimonide, Infrared radiation, Aluminum, Infrared photography, Antimony, Superlattices, Binary data, Group III-V semiconductors
Mid-wavelength infrared photodetectors incorporated into a unipolar barrier architecture with a bulk InAs<sub>x</sub>Sb<sub>1-x</sub> absorber and an AlSb barrier layer are demonstrated. An extended cutoff was achieved by increasing the lattice constant from 6.09 Å of the GaSb substrate to 6.13 Å using a 1.5 μm thick AlSb buffer layer. This enabled the growth of bulk absorber material with a higher antimony content, InAs<sub>0.81</sub>Sb<sub>0.19</sub>, and a greater than 5 μm cutoff. Transitioning the lattice to 6.13 Å also enabled the implementation of a simple binary AlSb layer as a unipolar barrier to block majority carrier electrons and reduce dark current noise. Individual test devices with 4 μm thick absorbers displayed 150 K dark current density, cutoff wavelength, quantum efficiency, and specific detectivity of 3 x 10<sup>-5</sup> A/cm<sup>2</sup>, 5.31 μm, 44 % at 3.4 μm, and 4.3 x 10<sup>11</sup> cmHz<sup>1/2</sup>/W at 5 μm, respectively. The instantaneous dark current activation energy at a given bias and temperature was determined via Arrhenius analysis from the dark current vs. temperature and bias data, and a discussion of valence band alignment between the InAs<sub>x</sub>Sb<sub>1-x</sub> absorber and AlSb barrier layers is presented. The carrier concentration, mobility, and lifetime of the bulk absorber material and the device performance will be presented and a discussed.
