Degradation of MgB2 thin films in water

We have studied the degradation of MgB₂ thin films, grown by hybrid physical-chemical vapor deposition (HPCVD), by submerging MgB₂ films into de-ionized water at different temperatures. The thickness, room temperature resistance, and superconducting transition were measured as a function of time in water and the temperature of the water. Results show that the films degrade faster at room temperature than at 0°C. The room temperature resistance increases with time. The thickness of the MgB₂ films decreases rapidly initially, but then saturates. The resultant material is amorphous and insulating. Both T_c(onset) and T_c(0) of the MgB₂ films decrease with time in water, while the superconducting transition become broader. The effects of the exposure to other solvents and photoresist were also studied, and it was found that isopropanol does not cause MgB₂ films to degrade.