Electrowetting at a liquid metal-semiconductor junction

Abstract

We report electrowetting at a liquid metal-semiconductor (Schottky) junction using of a mercury droplet resting on silicon. This is demonstrated using n-type and p-type single-crystal silicon wafers of different doping levels. The voltage-dependent wetting contact angle variation of the mercury droplet is observed to depend on both the underlying semiconductor doping density and type. The electrowetting behavior can be explained by the voltage-dependent modulation of the capacitance of a Schottky junction; current-voltage and capacitance-voltage measurements indicate this to be the case. A modified Young-Lippmann electrowetting equation—formulated using a well-established metal-semiconductor junction model—agrees well with the observations.