The effect of synthesis conditions and humidity on current-voltage relations in electrodeposited ZnO-based Schottky junctions.

Electrochemically produced ZnO/metal rectifying (Schottky) junctions can exhibit consistent barrier heights and high rectifying ratios when prepared using optimized electrolyte pH (6.5) and applied voltage (</=-1.1 V vs Ag/AgCl) conditions. An increase in soft breakdown for more acidic deposition electrolytes (pH 4) correlates with a diminished preferred orientation in the resulting ZnO electrodeposit. Forward-biased junctions exposed to increased relative humidities show increased current as a result of protonic conduction from water hydrolysis at the ZnO/air interface. At moderate to high relative humidities (50-85% RH), hydrophobic coatings improve the quality of the rectifying response by changing the wetting properties of the ZnO surface. Our findings suggest that electrodeposition, in conjunction with postdeposition surface coatings, can offer improved functionality for electron transport materials in wet or humid environments.