Color-Selective Schottky Barrier Modulation for Optoelectric Logic.

The limitation on signal processes implementable using conventional semiconductor circuits based on electric signals necessitates a revolutionary change in device structures such that they can exploit photons or light. Herein, we introduce optoelectric logic circuits that convert optical signals with different wavelengths corresponding to different colors into binary electric signals. Such circuits are assembled using unit devices in which the electric current through the semiconductor channel is effectively gated by lights of different colors. Color-selective optical modulation of the device is cleverly achieved using graphene decorated with different organic dyes as the electrode of a Schottky diode structure. The drastic change in the electrode work function under illumination induces a change in the height of the Schottky barrier formed at the electrode/semiconductor junction and consequent modulation of the electric current; we term the developed device a photonic barristor. We construct logic circuits using an array of photonic barristors and demonstrate that they execute the functions of conventional NAND and NOR gates from optical input signals.