Study of MgB2 ultra-thin films in submicron size bridges

We discuss a custom built hybrid physical chemical vapour deposition (HPCVD) system for MgB2 ultra-thin film deposition: construction, deposition process development, and optimization. Achieved films on SiC substrates have a critical temperature (Tc) ranging from 35K (10nm thick films) to 41K (40nm thick films). The 20nm thick unpatterned film had a room temperature resistivity of 13μΩ\ub7cm, whereas it becomes 50μΩ\ub7cm in sub-micrometer size bridges with a critical current density Jc (4.2K) up to 1.2 710^8A/cm2. The lower value of resistivity corresponds to the higher of both Tc and Jc. The surface roughness, measured with an atomic force microscope (AFM), is approximately 1.5nm