Photosensitive Graphene P-N Junction Transistors and Ternary Inverters.

We investigate the electric transport in a graphene-organic dye hybrid and the formation of p-n junctions. In the conventional approach, graphene p-n junctions are produced by using multiple electrostatic gates or local chemical doping, which produce different types of carriers in graphene. Instead of using multiple gates or typical chemical doping, a different approach to fabricate p-n junctions is proposed. The approach is based on optical gating of photosensitive dye molecules; this method can produce a well-defined sharp junction. The potential difference in the proposed p-n junction can be controlled by varying the optical power of incident light. A theoretical calculation based on the effective medium theory is performed to thoroughly explain the experimental data. The characteristic transport behavior of the photosensitive graphene p-n junction opens new possibilities for graphene-based devices, and we use the results to fabricate ternary inverters. Our strategy of building a simple hybrid p-n junction can further offer many opportunities in the near future of tuning it for other optoelectronic functionalities.