Anagrafe della ricerca

The nearly lattice-matched antimonide material system (i.e., GaSb, AlSb, InAs and their related compounds) represents the most credible alternative to mercury cadmium telluride (HgCdTe) in the infrared imaging technology. Antimonide-based type-II superlattice (T2SL) detectors hold the promise for the development of high-performance and low-cost mid-wavelength infrared (MWIR) photodetectors for navigation in low-visibility environments, weather surveillance, and search and rescue operations. III–V semiconductors are more robust than their II–VI counterparts due to stronger, less ionic chemical bonding. Besides the high quality, high uniformity, and stable nature of the material, the band structure flexibility of T2SLs enables novel detector architectures, making T2SLs probably the best realization of the material-by-design concept. Understanding the sophisticated physics of T2SLs is a crucial step towards the full development of this emerging technology. Commercial simulation tools successfully employed to design and optimize bulk HgCdTe detectors are not applicable to T2SLs, as complex quantum effects such as miniband transport and hopping between localized states cannot be described at a semiclassical level. In this project, we will address the sophisticated physics of carrier transport in T2SLs by means of the nonequilibrium Green’s function (NEGF) method, a state-of-the-art formalism for quantum device simulation. In short, the main objectives of the project are to provide the modeling tools to design superlattice detectors with higher operating temperatures, higher bandwidth, and improved detectivity. High-performance MWIR detectors are currently operated at cryogenic temperatures from 77 K to 140 K, which makes these devices expensive and bulky. Superlattice architectures with lower dark currents could provide high-performance at affordable costs.