Modulating the resistivity of MoS_2 through low energy phosphorus plasma implantation

摘要

Molybdenum disulfide (MoS_2) is a promising potential replacement for Si in future microelectronic devices. Integration in electronic devices will likely involve the growth or transfer of large-area MoS_2 films onto substrates and subsequent isolation of devices. In this paper, the effect of ion implantation on the electrical properties of MoS_2 is reported. Large-area ~4 layer MoS_2 films were implanted by low energy phosphorus plasma at biases of 100, 200, and 300 V and a dose of 1 × 10~(14)cm~(-2). Electrical measurements using patterned Ni/Au contacts show that after implantation, independent of bias, there is greater than a 10~4 increase in resistivity. TEM and Raman spec-troscopy suggest that the film is crystalline prior to and after ion implantation and annealing and that there is no measurable sputtering following implantation. This suggests that the increase in resistivity is likely the result of radiation damage in the MoS_2. The thermal stability of the increase in electrical resistivity was assessed by a series of 15 min anneals beginning at 325 ℃ in a sulfur overpressure and progressing up to 525 ℃ under an A1_2O_3 ALD cap. The resistivity increase remained unchanged after annealing. These results suggest that implant isolation could provide a preferable alternative to reactive ion etching or chemical etching for electrical isolation of MoS_2.