Raman investigation of the air stability of 2H polytype HfSe2 thin films


Hafnium diselenide (HfSe2) has a high theoretical carrier mobility but is among the most reactive transition-metal dichalcogenides (TMDs). Herein, we have investigated the air stability of 2H polytype HfSe2 single-crystal thin films by spectroscopic and microscopic techniques. Raman spectroscopy measurements in conjunction with atomic force microscopy reveal the formation of selenium-rich blisters on the surface of the crystals upon air exposure. Transmission electron microscopy analysis indicates that 2H-HfSe2 undergoes a spontaneous phase change to 1T-HfSe2. These results offer Raman spectroscopy as a fast, convenient, non-destructive technique to reliably monitor the surface degradation of TMDs and present an opportunity for further study of phase changes in this material.

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This work was made possible by support from C-SPIN, a funded center of STARnet, through a SRC program sponsored by MARCO and DARPA. Raman measurements were performed in the ACIF at the UC Riverside. TEM analysis was performed in the CFAMM at the UC Riverside. The authors thank Dr. Krassimir N. Bozhilov for his assistance with TEM analysis.

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Correspondence to Cengiz S. Ozkan.

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Work performed during postdoctoral studies at the University of California, Riverside.

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The supplementary material for this article can be found at https://doi.org/10.1557/mrc.2018.185.

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Cruz, A., Mutlu, Z., Ozkan, M. et al. Raman investigation of the air stability of 2H polytype HfSe2 thin films. MRS Communications 8, 1191–1196 (2018). https://doi.org/10.1557/mrc.2018.185

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