Kavli Affiliate: Ke Wang
| First 5 Authors: Aleksandar Radic, Aleksandar Radic, , ,
| Summary:
Two-dimensional (2D) materials are being widely researched for their
interesting electronic properties. Their optoelectronic, mechanical and thermal
properties can be finely modulated using a variety of methods, including
strain, passivation, doping, and tuning of defect density. However, measuring
defect densities, such as those associated with vacancy-type point defects, is
inherently very difficult in atomically thin materials. Here we show that
helium atom micro-diffraction can be used to measure defect density in
~15×20$mu$m monolayer MoS$_2$, a prototypical 2D semiconductor, quickly and
easily compared to standard methods. We present a simple analytic model, the
lattice gas equation, that fully captures the relationship between atomic Bragg
diffraction intensity and defect density. The model, combined with ab initio
scattering calculations, shows that our technique can immediately be applied to
a wide range of 2D materials, independent of sample chemistry or structure.
Additionally, favourable signal scaling with lateral resolution makes
wafer-scale characterisation immediately possible.
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