Low‐Energy Ion Scattering Fingerprints of Blue Phosphorus: Azimuthal Symmetry, Vacancy Sensitivity, and Experimental Protocol

ABSTRACT Blue phosphorus is the metastable hexagonal allotrope of two‐dimensional phosphorus and a wide‐gap semiconductor of growing interest for post‐graphene electronics. Its surface composition at the atomic‐layer level remains uncharacterized, however, because experimental low‐energy ion scattering (LEIS) on the nm‐scale samples currently available is not yet feasible. We present a comprehensive azimuth‐resolved multi‐ion BCA survey of LEIS from free‐standing single‐layer blueP, designed from the outset as a practical protocol for the experimental campaigns that will follow once larger‐area samples become available. The simulations combine NLH interatomic potentials, auto‐calibrated Lindhard–Scharff electronic stopping, temperature‐dependent thermal vibrations, and Hagstrum ion‐survival; we check the kinematic and detector‐bookkeeping consistency of the framework against Si(100)/He + , where the simulated peak matches the analytical prediction to within 0.1% of the incident energy. The azimuthal scan of He + reproduces the sixfold periodicity that the P‐3m1 symmetry of the bilayer requires. The quantitative content of the scan (peak yields of 22.8% at the zigzag direction and 15.3% at the armchair direction against a blocked‐azimuth background below 0.4%, Wilson 95% upper bound at N = 900) gives a peak‐to‐trough contrast in excess of 50 that distinguishes blueP from orthorhombic black phosphorus and provides the reference numbers against which an experimental scan can be tested. Three further findings—kinematic discrimination among the noble gases (with Ar + kinematically forbidden beyond θ max = 50.83°), a ratiometric He + /Ne + vacancy probe, and an anti‐channelling temperature dependence—together specify a practical experimental protocol.

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