Emerging Type-II Superlattices of InAs/InAsSb and InAs/GaSb for Mid-Wavelength Infrared Photodetectors

Mid-wavelength infrared (MWIR) photodetectors (PDs) are highly essential for environmental sensing of hazardous gases, security, defense, and medical applications. Mercury cadmium telluride (MCT) materials have been the most used detector in the MWIR range. However, it is plagued by several challenges including toxicity concerns, a high rate of Auger nonradiative recombination, a large band-to-band (BTB) tunneling current, nonuniformity, and the need for cryogenic cooling. Theoretically, it is predicted that type-II superlattice (T2SL) materials can emerge as an alternative with the potential to outperform the current state-of-the-art MCT PDs due to suppression of Auger recombination associated with bandgap engineering and reduced BTB tunneling current caused by the larger effective mass. Based on this theoretical prediction, it is believed that T2SL have the potential to operate at high temperatures and overcome the size, weight, and power consumption limitations of MCT. Herein, a detailed review of the fundamental material properties of T2SL PDs is provided while providing a comparison of the optical and electrical performances of Ga-free (InAs/InAsSb) and Ga-based (InAs/GaSb) T2SL PDs. Finally, recent advances in IR detection technologies including focal plane arrays and quantum cascade infrared photodetectors are explored.