Low operating voltage, large area, mm scale channel length graphene transistor with current saturation and its channel length dependent transport properties

Large area graphene always acts as a semi metal and due to which large channel length graphene transistor with current saturation is not possible. However, it is theoretically predicted that the Graphene band gap open up to 0.85eV due to ionic polarization of lighter Li⁺ ion. To realize that prediction, we fabricated large channel length GFET with Li₅AlO₄ gate dielectric in bottom gate top contact geometry that need only 2.0 V gate and source voltage to operate the device with good current saturation. Thermally deposited Ag/MoOx has been used as source/drain electrode for this device. The length scaling of these GFETs has been studied with channel length variation within a range from 0.2 mm to 5.7mm. This data indicates that the Dirac point voltage can be minimize by varying channel length. Additionally, it is observed that the GFET of 1.65mm channel length show best device performance with good current saturation. This particular GFET show the hole mobility of 312 cm²/V.s with on/off ratio. The maximum normalized transconductance was found to be 5.31mS with 0.2mn channel length at a bias of -2V which indicates the high efficiency of gate oxide and graphene channel. (author)