Passivation Technologies for Improved Operability in HgCdTe Focal Plane Arrays

High-performance infrared detectors are mission-critical components of each layer of the Ballistic Missile Defense System. MDA is investing heavily in technologies that enhance producibility/operability of LWIR/VLWIR infrared focal plane arrays (FPAs), and reduce BMDS life cycle costs. HgCdTe is clearly the material of choice for these IRFPAs, but presents numerous challenges, including trap-assisted tunneling which results in excessive dark currents. Such defects in HgCdTe FPAs must be addressed for Next Generation detectors to deliver on their promise of better discrimination of low temperature targets against low temperature backgrounds, and large-format arrays. In Phase I, hydrogenation proved effective in passivating defects in MBE-grown HgCdTe/ZnCdTe diodes. Amethyst will team with BAE in Phase II to develop hydrogen passivation technology to improve operability and yields of LWIR/VLWIR FPAs manufactured in LPE-grown HgCdTe/ZnCdTe. The program involves development of tailored hydrogenation and integration schemes targeting passivation of the defects, i.e. traps, responsible for the tunneling current. Amethyst’s research plan also includes parametric studies to optimize passivation techniques for BAE’s process flow. Hydrogenated/non-hydrogenated (striped) hybridized arrays will be characterized to quantify operability gains. Hydrogenation is readily implemented as a straightforward add-on process with little or no impact on the conventional manufacturing flow.