Quantum well infrared photocathode having negative electron affinity surface

摘要

An infrared photocathode comprises an infrared radiation absorbing structure based on multiple quantum well (MQW) material on top of an electron conducting contact layer having a negative electron affinity back surface. In the first photocathode, a top contact layer is etched to form a transmissive diffraction grating to aid photon absorption in the MQW material. In the second photocathode, a plurality of spaced apart MQW structures form a diffraction grating which aids photon absorption in the MQW material.