Progress of long wavelength infrared focal plane arrays based on antimonide compounds superlattice

Abstract

<p indent=0mm>The research of antimonide compounds began with 1950s. With the appearing of superlattice concept and energy band engineering in the 1970s, the potentials in infrared detection of antimonide compounds gradually emerged. Due to the reality demand, epitaxy and preparation technologies of antimonide-based materials have achieved rapid progress. The rapid advance of T2SL also benefits from the previously five decades ago of development of III-V group materials and devices research. The development of InAs/GaSb type-II superlattices (T2SLs) results from two primary motivations: the InAs/GaSb superlattice has more apparent advantages than HgCdTe in low cost, reproducibility, operability and high uniformity, especially for long wavelength detector. Secondly, the Auger recombination probability of type II superlattices is lower than that of HgCdTe, which means that the infrared detector of type II superlattice has a lower dark current or a higher working temperature than that of HgCdTe detector. And improving the working temperature of the long-wave focal plane is crucial for reducing the power consumption, size and weight of the imaging system. In addition, the atmosphere window with highest transmittance is located at the range of <sc>8−14 μm.</sc> And the emitted infrared radiation by an object at room temperature <sc>(300 K)</sc> has a wavelength of about <sc>10 μm.</sc> Therefore, long wavelength infrared detection is extremely valuable for InAs/GaSb type-II superlattices. Compared with HgCdTe device, T2SL detectors can provide equivalent or better performance under the same cutoff wavelength. But the short minority carrier lifetime of InAs/GaSb superlattice cause a high level of generation-recombination current (<italic>J</italic>_gr). In order to suppress <italic>J</italic>_gr and other dark current, the different device structures like W-structure, PπMN structure, CBIRD and unipolar barrier were put forward and employed in the detectors. As a result, the dark current and impedance was greatly improved. Furthermore, with the putting forward of InAs/InAsSb superlattice, the defects level in band gap introduced by Ga were avoided, and the minority carriers lifetime were effectively improved. The reproducibility, operability and uniformity of T2SL bring more advantages than HgCdTe detector with the sustainable developement of T2SL technologies and theories.