The fabrication and electrical characteristics of vacuum-evaporated thin film AlCdSAl, AlCdSAu, AuCdSAl and AuCdS Schottky barrier diodes are described; the CdS films were produced by evaporating a mixture of CdS and S 2 powders from a single source onto a heated substrate. Particularly good diode action is observed for AlCdS barriers, despite the fact that these are normally ohmic. Diode action is observed in each case between the underlying metal and the semiconductor, and this is attributed to an excess of semiconductor acceptor surface states at such interfaces. Results are exemplified for the four configurations at 20°C, which exhibit (a) reverse-forward resistance ratios of about 10 5, (b) reverse voltage capabilities of 8–10 V, (c) space-charge-limited current behaviour at forward voltages above about 1 V, and (d) voltage dependences as high as V 8 at lower voltages. Measurements on the AlCdS barriers yielded a barrier height ϕ Bn = ∼0.7 eV.