Superconducting Magnesium Diboride Thin Films for Ground Receiver Detectors

Superconducting films of magnesium diboride (MgB2) are very attractive for a range of detector and telecommunications applications owing to the high critical temperature of these films, ~40 K, which greatly simplifies the cooling requirements. We propose to develop a reactive evaporation technique for the deposition of MgB2 thick films on wafers up to at least 4" diameter, and an etch back and passivation process to produce high-quality thin films that are needed for the development of superconducting single photon detectors (SNSPDs) and THz hot electron bolometer (HEB) mixers. Currently there is no domestic commercial source for MgB2 films; the only commercial source we are aware of is an overseas vendor that can supply films only on very small (<1 cm2) chips. In Phase I, we demonstrated the feasibility of the etch back and passivation process, and completed designs for the reactive evaporation system that we will build in Phase II and develop a wafer-scale process for the deposition and production of MgB2 films.