LAUSR

Graphene has been extensively studied as highly flexible and optically transparent contacts in semiconductor devices, such as photodetectors, solar cells, and light emitting transistors. A Schottky barrier forms at the interface between graphene and semiconductor, whose height has an exponential impact on the current. In this work, image-charge-induced barrier lowering (BL) in graphene–semiconductor contacts is examined and compared to that in metal Schottky contacts. The results show that despite graphene being a semimetal with vanishing density-of-states at the Dirac point, the image-charge-induced BL can be significant. Even in an undoped graphene–semiconductor contact, the BL value can be more than 50% of that of a metal Schottky contact. The ratio of BL in a graphene–semiconductor contact to that in a metal–semiconductor contact increases as the graphene doping density increases and as the semiconductor dielectric constant decreases. An empirical expression for estimating the image-charge-induced BL in graphene–semiconductor contacts is provided.