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

• I–V–T characteristics of Au/graphene/n-type Ge SBD.
• Anomalous temperature dependence of Schottky barrier parameters of Au/graphene/n-type Ge SBD.
• Single Gaussian distribution of barrier height in Au/graphene/n-type Ge SBD.
• The graphene interlayer improves barrier homogeneity associated passivating the Ge surface.

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.

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