CMOS-based VUV detectors for the Solar Orbiter

An Italian working group has been formed in order to develop vacuum UV (VUV) detectors based on CMOS imagers. The aim of this paper is to describe the concepts of such devices and to show some results pointing out their feasibility. These innovative detectors are proposed as a viable solution for the remote sensing VUV imagers and spectrometers on the Solar Orbiter. The technological background consists of a well-established expertise on novel materials (such as diamond and nitrides) applied to VUV photon detection and the currently available technology of (bump-) bonding CMOS imagers on such layers. Flip-chip imagers offer several advantages in terms of sensitivity, radiation hardness, solar blindness, mechanical and thermal properties, and leakage current. Another important feature is the on-chip read-out electronics that is typical of CMOS imagers, providing a compact detector system. A technique implementing photon-counting capability is described as well.