We have fabricated C60-based n-type organic field-effect transistors(OFETs) with different buffer layers with n-doped silicon substrate as the gate electrode and SiO2/PMMA as the dielectric.The performance of different modified devices is also investigated.Compared with the one without modified layer,the modified ones show a certain improvement and the bi-layer device shows the highest mobility,which is up to 1.6×10-2 cm2/V·s.Furthermore,the operation mechanism of the bi-layer device has been an...