CHEMICAL VAPOR-DEPOSITION OF NOVEL ELECTRONIC MATERIALS FROM CARBON-DISULFIDE

An organic amorphous semiconductor with unusual electrical switching capability has been synthesized by the direct decomposition of carbon disulfide. Metallic black highly conducting (above 10(2) OMEGA-1 cm-1) thin films of approximate composition C3S have been prepared by the simple passage of dilute carbon disulfide vapors over an incandescent tungsten filament. Film growth rates greater than 10 mum h-1 are observed. The coatings are hard, adherent on a wide variety of substrates, thermally stable, and remarkably inert to all but the most severe mineral acid digestion. The carbon sulfide solids behave like varistors, following Ohm's law over many decades of current up to a threshold voltage, typically 1-10 V, beyond which the current surges, independent of applied voltage. The threshold voltage is uniquely temperature dependent, reaching a maximum as the temperature is reduced from room temperature, then decreasing once again at cryogenic temperatures.