A III-nitride Layered Barrier Structure for Hyperspectral Imaging Applications

We report on a novel photodetector structure based on III-nitride materials. A layered configuration is used to create a barrier with voltage-tunable height. The barrier is used as a filter on photoexcited holes and electrons, and could form the basis for a dynamically tunable pixel in a hyperspectral imaging array. This would eliminate the need for external gratings and filters used in conventional hyperspectral instruments; in addition, the tunability of pixels allows decrease of the array dimension by one. The III-nitride materials family is a good candidate for this device, combining large band offsets with the ability for epitaxial growth. We have demonstrated the feasibility of using III-nitride materials to fabricate layered tunnel barriers, and have demonstrated tunability of photodetection using these structures. External quantum efficiencies of > 12% have been achieved with prototype devices.