INFRA-RED DETECTOR ELEMENTS AND THEIR MANUFACTURE

摘要

1 PHB 32631 An infra-red radiation detector element and its manufacture is disclosed. The detector element has a mesa of infra-red sensitive material, e.g. cadmium mercury telluride, with separate metal electrodes formed on side-walls of the mesa from a metal layer. This permits a significant proportion of the current flow occurring between the electrodes in operation of the element to pass across the bulk of the mesa between its side-walls and not adjacent its top surface where the carrier recombination velocity may be higher. The mesa is formed by ion-etching using a masking layer e.g. of photoresist, and this permits reproducible etching over a uniform depth and the obtaining of a topographically rough surface to which the subsequently-deposited metal layer can have good adhesion. The electrodes are formed from this layer by a lift-off technique using the same masking layer. The ion-etch definition of the mesa can also be used to etch unmasked parts of a passivating layer on the element surface without any significant undercutting.