Radiation tolerance of a dual-band IR detector based on a pBp architecture

Abstract

Infrared (IR) detectors operated in the space environment are required to have high performance while being subjected to a variety of radiation effects. Sources of radiation in space include the trapped particles in the Van Allen belts and transient events such as solar events and galactic cosmic rays. Mercury cadmium telluride (MCT)-based IR detectors are often used in space applications because they have high performance and are generally relatively tolerant of the space environment when passivated with CdTe; often, the readout-integrated circuit is far more susceptible to radiation effects than the detector materials themselves. However, inherent manufacturing issues with the growth of MCT have led to interest in alternative detector technologies including type-II strained-layer superlattice (T2SLS) infrared detectors with unipolar barriers. Much less is known about the radiation tolerance properties of these SLS-based detectors compared to MCT. Here, the effects of 63 MeV protons on variable area, single element, dual-band InAs/GaSb SLS detectors in the pBp architecture are considered. When semiconductors devices are irradiated with protons with energies of 63 MeV the protons are capable of displacing atoms within their crystalline lattice. The SLS detectors tested here utilize a pBp architecture, which takes advantage of the higher mobility electrons as the minority photocarrier. These detectors are also dual-band, implying two absorbing regions are present and separated by the unipolar barrier. The absorbers have cutoff wavelengths of roughly 5 and 9 μm allowing for mid-wave (MWIR) and long-wave (LWIR) infrared detection, respectively. The radiation effects on these detectors are characterized by dark current and quantum efficiency as a function of total ionizing dose (TID) or, equivalently, the incident proton fluence.