Ionic liquid gel gate tunable <i>p</i>-Si/MoS₂ heterojunction <i>p</i>-<i>n</i> diode

Monolayer MoS₂ crystals investigated in this work were grown via chemical vapor deposition on Si/SiO₂ substrates. Using a wet KOH etch, these crystals were transferred on to the edge of a freshly cleaved p-Si/SiO₂ wafer where they formed mechanically robust heterojunctions at the p-Si/MoS₂ interface. Electrical characterization of the device across the junction yielded an asymmetric I-V response similar to a p-n diode. The I-V response was electrostatically tunable via an ionic liquid gel gate. This is the first report demonstrating reversible gate control of the p-Si/MoS₂ diode current by several orders of magnitude while lowering its turn-on voltage. Fermi energy level shifts within the MoS₂ band gap by the gate was believed responsible for the observed effects. The ease of fabrication, low operating voltages (< ±2V) and moderately high throughput currents (~ 1mA) are attractive features of this diode, especially for use in sensors and power saving electronics.