Non-negligible influence of vacancies and interlayer coupling on electronic properties of heavy ion irradiated SnSe₂ FETs

Influences of swift heavy ion (SHI) irradiation induced defects on electronic properties of the bulk SnSe₂ based FETs are explored. Latent tracks and amounts of Se vacancies in the irradiated SnSe₂ were confirmed. Red shift of the A_1g peak indicates that the resonance frequency of the phonons is reduced due to the defect generation in SnSe₂. The source–drain current I_ds increased at ion fluence of 1 × 10¹⁰ ions⋅cm⁻², which was attributeded to the irradiation caused Se vacancies, which hence increases the concentration of conduction electrons. The carrier mobility was about 16.9 cm²⋅V⁻¹⋅s⁻¹ for the devices irradiated at ion fluence of 1 × 10⁹ ions⋅cm⁻², which benefited from heavy ion irradiation enhanced interlayer coupling. The mechanism of device performance optimization after irradiation is discussed in detail. This work provides evidence that, given the electronic properties of two-dimensional material-based device, vacancies and interlayer coupling effects caused by SHI irradiation should not be ignored.