Performance Improvement of HfS2 Transistors by Atomic Layer Deposition of HfO2

Hafnium disulfide (HfS2) is one of the transition metal dichalcogenides which is expected to have the high electron mobility and the finite bandgap. However, the fabrication process for HfS2 = based electron devices is not established, and it is required to bring out the superior transport properties of HfS2. In this report, we have investigated the effects of the atomic layer deposited HfO2 passivation on the current properties of HfS2 transistors. HfO2 passivation of the HfS2 surface enhanced the drain current and significantly reduced the hysteresis. Moreover, HfO2 passivation allows the use of a higher annealing temperature and further improvement of the drain current.