Films of lanthanum sulfide were prepared by vapor deposition of the separate constituents onto heated sapphire substrates. The technique can be used to produce films over the entire range of composition from La2S3, which is an insulator, to La3S4 which is a metal and a superconductor. This family of materials shows promise for use in three-terminal superconducting devices based on the metal field effect.
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The authors would like to thank H. Jaeger and E. D. Dahlberg for helpful discussions. This work was supported in part by the Air Force Office of Scientific Research under Grant 84-0347.