Work function modulation of electrodes contacted to molybdenum disulfide using an attached metal pad

The transport properties of electronic devices fabricated using two-dimensional materials are severely affected by the Schottky barrier at the contact of an electrode. The Schottky barrier height exhibits a strong correlation with the work function of the electrode. We observed rectifying current–voltage characteristics for a back-gated field effect transistor with a channel of molybdenum disulfide and Al electrodes, where one of the electrodes is attached to a Au pad. This result is explained in terms of the increase in the effective work function of the Al electrode attached to the Au pad. The dependence of a photocurrent on the bias voltage exhibited an opposite tendency to the current–voltage characteristics; this is also attributed to the work function modulation of the electrode, thus resulting in the variation in the Schottky barrier height.