Measurement of Vacuum Ultraviolet Radiation of Low-Pressure Mercury Lamps Using Photoconductors Made of Synthetic Diamond Films

Abstract

A new type of robust photoconductor made of synthetic diamond films was evaluated for measurement of vacuum ultraviolet (VUV) radiation irradiated by low-pressure mercury lamps. It was demonstrated that the diamond sensors are suited to directly measure intensity of 185 nm line among various radiations from low-pressure mercury lamps. Decrease in contact angles of water droplets on UV-treated glass substrates was more closely correlated with the irradiance of 185 nm as compared to that of 254 nm from low-pressure mercury lamps, indicating importance of direct monitoring of the former. The diamond sensors were very stable and did not degrade for 100 hours under the 185 nm irradiation of about 2 mW/cm², showing potential usefulness of the sensors for monitoring and controlling of various VUV processes.