Optical phenomena of irradiation induced molybdenum disulfide*

Irradiation introduces damage cascades, destroys the periodicity of the lattice, and pushes the material away from equilibrium. In this contribution, we utilize heavy ion and gamma irradiations to alter the optical properties of two-dimensional (2D) materials such as MoS₂. Irradiation offers a pathway to introduce desired defect densities to any given material, and, in case of low-dimensional materials, can be used to control physical properties. Defects introduced using irradiation were characterized using transmission electron microscopy (TEM) and photoluminescence (PL) measurements. We primarily focus our attention on the behavior of valley excitons, as they dominate the optical response of the material even when the system is in equilibrium and reveal the emergence of dark excitonic states in the K-valley. With this work, we offer insight into how increased defect density can potentially engineer magnetism in 2D MoS₂.

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2. A. V. Stier et al., Nat Commun., 7:10643 (2016)

3. M. Zhang et al., J. Phys.: Condens. Matter 30 265502 (2018)