Advanced Sensor Materials for Space

Advanced technology and circuit architecture is under investigation for high performance, infra-red, and low power electronics. GaSb substrates have advantages that are attractive for implementation of very long wavelength infrared (VLWIR) detectors with higher operating temperatures for spaced based and stealth applications. A significant aspect inhibiting widespread commercial application of GaSb wafers for VLWIR is the lack of transparency beyond 15m. Due to antisite and other point defects in undoped GaSb substrates, intrinsic GaSb is still slightly p-type which strongly absorbs VLWIR wavelengths. Even for low n-type GaSb substrates, the substrate requires backside thinning for IR transparency. In Phase I, ultra-low n-type GaSb substrates (n<4x1015/cm3) were fabricated. For the first time, GaSb VLWIR transparency was exhibited to 25m with 35X improvement in %transmittance. Elimination of backside thinning for VLWIR devices should be enabled. A Phase II manufacturing process for ultra-low n:GaSb will be established. Melt-interface thermodynamics established in Phase I will be optimized. Theoretical boule cooling ramp rates will be further engineered with an encapsulating jacket. Strained-layer-superlattice (SLS) and VLWIR device processing will be implemented in conjunction with Lockheed-Martin, Raytheon, and Teledyne Scientific. Phase III commercialization probability for ultra-low doped n:GaSb is high, with established customers expressing commitment.