Pyrite (FeS2) thin films prepared by spray method using FeSO4 and (NH4)2Sx

A simple spray method for the preparation of pyrite (FeS2) thin films has been studied using FeSO4 and (NH4)(2)S-x as precursors for Fe and S, respectively. Aqueous solutions of these precursors are sprayed alternately onto a substrate heated up to 120degreesC. Although Fe-S compounds including pyrite are formed on the substrate by the spraying, sulfurization of deposited films is needed to convert other phases such as FeS or marcasite into pyrite. A single-phase pyrite film is obtained after the sulfurization in a H2S atmosphere at around 500degreesC for 30 min. All pyrite films prepared show p-type conduction. They have a carrier concentration (p) in the range 10(16)-10(20) cm(-3) and a Hall mobility (mu(H)) in the range 200-1 cm(2)/ Vs. The best electrical properties (p = 7 x 10(16) cm(-3), mu(H) = 210cm(2)/Vs) for a pyrite film prepared here show the excellence of this method. The use of a lower concentration FeSO4 solution is found to enhance grain growth of pyrite crystals and also to improve electrical properties of pyrite films. (C) 2002 Elsevier Science B.V. All rights reserved.