Superconducting thin films of MgB2 on Si by pulsed laser deposition

Superconducting thin films have been prepared on Si-substrates, using pulsed laser deposition from a target composed of a mixture of Mg and MgB2 powders. The films were deposited at room temperature and annealed at 600 degreesC. The zero resistance transition temperatures were 11-15.5 K, with an onset transition temperature of 27 K. Special care has been taken to avoid oxidation of Mg in the laser plasma and deposited film, by optimizing the background pressure of Ar gas in the deposition chamber. For this the optical emission in the visible range from the plasma has been used as indicator. Preventing Mg from oxidation was found to be essential to obtain superconducting films. (C) 2001 Elsevier Science B.V. All rights reserved.