Long and Very Long Wavelenght Non-equilibrium Superlattice Infrared Detectors

We propose a new generation of non-equilibrium, high efficiency long and very long wavelength infrared (8 microns and longer) superlattice-based detectors that operate in the 40 to 77 K temperature range. This technology will lead to the possibility of improving the performance of current infrared focal plane arrays. It will also permit the creation of very long wavelength infrared detection capabilities that are necessary for a variety of MDA missions. We plan to achieve the objectives by combining the advantages of the molecular beam epitaxy crystal growth technique and an innovative non-equilibrium device architecture that will decrease the dark current. In addition, we plan to introduce superlattice structures to control the energy bandgap more precisely. For the most frequently used infrared photon detecting material bulk HgCdTe, a small variation in the CdTe mole fraction causes a big change in the energy gap. However, the gap is determined by layer thicknesses in a superlattice, which can be better controlled. We propose to use HgTe/CdTe superlattice infrared materials grown by molecular beam epitaxy directly on CdTe/Si or CdZnTe bulk substrates. This will make it possible to produce high quality absorber layers with lower defect densities, and in turn, high performance detectors with lower dark currents and improved detectivities.