OPTICAL-EMISSION STUDY OF THE LASER-PLASMA PLUME PRODUCED DURING DIAMOND-LIKE CARBON THIN-FILM PREPARATION

We have studied the application of the diamondlike carbon (DLC) film a s a protective coating layer for high temperature superconducting thin films. Recently, the DLC film was proposed as an attractive material for field electron emitter device. We report on spectroscopic properti es of the KrF laser plasma plume produced during the DLC thin film dep osition. Optical emission measurements showed appearance of such neutr al and ionic species as H, C, C+, CH, CH+, C2H+. Strong emission from neutral and ionic molecules CH, C-2, C2H+ produced by the reaction in the gaseous phase has been observed with the ambient hydrogen gas pres sure increase. The calculated velocities of CH and C2H+ molecules at t he distances of 10-20 mm from the target are found to be 5.0 x 10(3) m /s and 9.1 x 10(3) m/s, correspondingly. The properties of the DLC thi n films are strongly affected by the laser plasma plume dynamics. The DLC film deposited on MgO (100) at room temperature and 200 mTorr hydr ogen pressure was almost transparent in the visible light range and ha d an optical band energy gap of 2.0 eV, which is about half of that of a diamond. (C) 1998 Elsevier Science S.A.