Reversible crystalline-to-amorphous phase transformation in monolayer MoS2 under grazing ion irradiation

P Valerius and S Kretschmer and BV Senkovskiy and SL Wu and J Hall and A Herman and N Ehlen and M Ghorbani-Asl and A Gruneis and AV Krasheninnikov and T Michely, 2D MATERIALS, 7, 025005 (2020).

DOI: 10.1088/2053-1583/ab5df4

By combining scanning tunneling microscopy, low-energy electron diffraction, photoluminescence and Raman spectroscopy experiments with molecular dynamics simulations, a comprehensive picture of the structural and electronic response of a monolayer of MoS2 to 500 eV Xe+ irradiation is obtained. The MoS2 layer is epitaxially grown on graphene/Ir(1 1 1) and analyzed before and after irradiation in situ under ultra-high vacuum conditions. Through optimized irradiation conditions using low-energy ions with grazing trajectories, amorphization of the monolayer is induced already at low ion fluences of ions cm(-2) and without inducing damage underneath the MoS2 layer. The crystalline-to-amorphous transformation is accompanied by changes in the electronic properties from semiconductor-to-metal and an extinction of photoluminescence. Upon thermal annealing, the re-crystallization occurs with restoration of the semiconducting properties, but residual defects prevent the recovery of photoluminescence.

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