Crossover between Photochemical and Photothermal Oxidations of Atomically Thin Magnetic Semiconductor CrPS4

Abstract

Many two-dimensional (2D) semiconductors represented by transition metal dichalcogenides have tunable optical bandgaps in the visible or near IR-range standing as a promising candidate for optoelectronic devices. Despite this potential, however, their photoreactions are not well understood or controversial in the mechanistic details. In this work, we report a unique thickness-dependent photoreaction sensitivity and a switchover between two competing reaction mechanisms in atomically thin chromium thiophosphate (CrPS4), a two-dimensional antiferromagnetic semiconductor. CrPS4 showed a threshold power density 2 orders of magnitude smaller than that for MoS2 obeying a photothermal reaction route. In addition, reaction cross section quantified with Raman spectroscopy revealed distinctive power dependences in the low and high power regimes. On the basis of optical in situ thermometric measurements and control experiments against O2, water, and photon energy, we proposed a photochemical oxidation mechanism involving singlet O2 in the low power regime with a photothermal route for the other. We also demonstrated a highly effective encapsulation with Al2O3 as a protection against the destructive photoinduced and ambient oxidations.

arXiv comment24 pages, 5 figures

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Cited by in corpus (7)

• Polarized Raman Spectra and Complex Raman Tensors of Antiferromagnetic Semiconductor CrPS4
• Magnetic order in van der Waals antiferromagnet CrPS4: anisotropic H-T phase diagrams and effects of pressure
• Magnon-magnon interaction and magnon relaxation time in ferromagnetic Cr2Ge2Te6 monolayer
• Resonant Raman Scattering of Few Layers CrBr${}_3$
• Parameter free treatment of a layered correlated van der Waals magnet: CrPS${}_4$
• Tunable linear and nonlinear anomalous Hall transport in two-dimensional CrPS${}_4$
• Activated Migration of Localized Ligand-Field Excitons in Atomically Thin CrCl3