Temperature dependent current-voltage characteristics of Au/n-type Ge Schottky barrier diodes with graphene interlayer

Current-voltage (I-V) characteristics of Au/n-type Ge Schottky barrier diodes (SBDs) with and without graphene interlayer were investigated in the temperature range of 180-340 K. For both devices, the Schottky parameters -such as the barrier height and ideality factor-showed strong temperature dependence, indicating a deviation of the I-V characteristics from what the thermionic emission (TE) mechanism predicts. On the basis of the TE theory along with the assumption that the barrier height takes on a Gaussian distribution, the temperature dependence of the I-V characteristics of the Au/n-type Ge SBDs with and without graphene interlayer was explained in terms of Schottky barrier inhomogeneity. Experimental results reveal the existence of a double Gaussian distribution of barrier height in the Au/n-type Ge SBD, whereas only a single Gaussian distribution of barrier height existed in the Au/graphene/n-type Ge SBD. Furthermore, the degree of barrier inhomogeneity of the Au/graphene/n-type Ge SBD is lower than that of the Au/n-type Ge SBD. The superiority of the Schottky barrier for the Au/graphene/n-type Ge SBD could be associated with the passivation of the Ge surface by the graphene interlayer.