▎ 摘　　要

We investigate electronic transport in single layer graphene coupled to superconducting electrodes. In these Josephson transistors, we observe significant suppression in the critical current I-c and large variations in the product IcRn in comparison to theoretical predictions in the ballistic limit. We show that the depression of I-c can be explained by premature switching in underdamped Josephson junctions described within the resistively and capacitively shunted junction (RCSJ) model. By considering the effect of premature switching and dissipation, the calculated gate dependence of product IcRn agrees with experimental data. Our discovery underscores the crucial role of thermal fluctuations in electronic transport in graphene Josephson transistors. (C) 2009 Elsevier Ltd. All rights reserved.