Physica C 190 ( 1991 ) 151-153 North-Holland PHYSICA Mercury-sensitized photo-induced chemical vapor deposition of YBa2Cu3Ox films Hideaki Zama and Shunri Oda Department of Physical Electronics, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152, Japan Takayuki Miyake and Takeo Hattori Department of Electrical and Electronic Engineering, Musashi Institute of Technology, TamazutsumL Setagaya-ku, Tokyo 158, Japan Low-temperature growth of YBaCuO films by photo-induced chemical vapor deposition using I]-diketonate complex and N20 is described. The mercury-sensitization technique is employed. Cu-oxide films are deposited at a substrate temperature T~ub = 120 ° C. Highly oriented Cu20 films are obtained on MgO substrate. YBaCuO films are deposited at Tsub = 215 ° C. The film composition as analysed by energy-dispersive X-ray spectrometry is nearly 1 : 2: 3 ( = Y: Ba: Cu). The structure of the YBa2Cu3Ox film is the amorphous phase. 1. Introduction Chemical vapor deposition (CVD) is a promising method for the preparation of high-quality epitaxial films of oxide superconductors at a low temperature. To date, however, a deposition temperature higher than 650°C is required to ob- tain high-To films of the YBa2Cu3Ox structure. Several at- tempts have been made to reduce the deposition tempera- ture of CVD of oxide superconductor films including the application of plasma [ 1,2 ] or UV-light [ 3,4 ]. Three major effects expected for the UV-light in the CVD process are (i) promotion of decomposition of ~diketonate complex on the basis of strong absorption due to the n-n* transition, (ii) enhancement of migration of species on the growing surface and (iii) generation of atomic oxygen as an active oxidizing agent. However, the effects of UV-light irradiation so far were limited to the improvement of the surface morphology [ 3 ] or the crystaUine orientation [ 4 ] of metal-oxide films. The enhancement of decomposition of I]-diketonate complex was not reported. This paper reports that it is possible to decompose 13-di- ketonate complex with N20 as an oxidizing agent under UV irradiation with mercury sensitization at low temperature. 2. Experimental Precursors used for CVD of YBaCuO films were I~-dike- ~I.0 ,n v z N~ 0 r-~ 100 SUBSTRATE D \ % G \ b % \ % \ \ \ Q \ \ I ! 150 200 TEMPERATURE (°C) Fig. 1. Film thickness vs. substrate temperature for Cu-oxide films with mercury-sensitized UV-light assisted decomposition of Cu(DPM)2. The vaporizer temperature of Cu(DPM)2 was 120°C, the carrier gas flow rate of Cu(DPM)2 was 20 seem, the flow rate of N20 was l0 seem, and the reactor pressure was 5 Torr. The gas-transfer-tube temperature is 150°C. o: without mercury-sensitization, O: without UV-irradiation. 0921-4534/91/$03.50 © 1991 Elsevier Science Publishers B.V. All fights reserved.