Chhor Yi Ly, Chenda Vong, Tharith Sriv, Hyeonsik Cheong
{"title":"Raman spectroscopy of atomically thin HfX2 (X=S, Se)","authors":"Chhor Yi Ly, Chenda Vong, Tharith Sriv, Hyeonsik Cheong","doi":"10.1088/2053-1583/ad70c8","DOIUrl":null,"url":null,"abstract":"We investigated interlayer modes of few-layer HfX<sub>2</sub> (X = S, Se) by using low-frequency micro-Raman spectroscopy with three excitation energies (1.96 eV, 2.33 eV, 2.54 eV) under vacuum condition (∼10<sup>−6</sup>Torr). We observed interlayer modes in HfSe<sub>2</sub> when the 2.54 eV excitation energy was used. The low-frequency Raman spectra reveal a series of shear and breathing modes (<50 cm<sup>−1</sup>) that are helpful for identifying the number of layers. The in-plane <italic toggle=\"yes\">E</italic><sub>g</sub> and out-of-plane <italic toggle=\"yes\">A</italic><sub>1g</sub> modes of HfSe<sub>2</sub> are located at ∼150 cm<sup>−1</sup> and ∼200 cm<sup>−1</sup>, respectively. In HfS<sub>2</sub>, in-plane <italic toggle=\"yes\">E</italic><sub>g</sub> and out-of-plane <italic toggle=\"yes\">A</italic><sub>1g</sub> optical phonons are observed at ∼260 cm<sup>−1</sup> and ∼337 cm<sup>−1,</sup> respectively. The in-plane and out-of-plane force constants of atomically thin HfSe<sub>2</sub> are obtained to be 1.87 × 10<sup>19</sup>N m<sup>−3</sup> and 6.55 × 10<sup>19</sup>N m<sup>−3</sup>, respectively, by fitting the observed interlayer modes using the linear chain model. These results provide valuable information on materials parameters for device designs using atomically-thin layered HfX<sub>2</sub> (X = S, Se).","PeriodicalId":6812,"journal":{"name":"2D Materials","volume":null,"pages":null},"PeriodicalIF":4.5000,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"2D Materials","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1088/2053-1583/ad70c8","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
We investigated interlayer modes of few-layer HfX2 (X = S, Se) by using low-frequency micro-Raman spectroscopy with three excitation energies (1.96 eV, 2.33 eV, 2.54 eV) under vacuum condition (∼10−6Torr). We observed interlayer modes in HfSe2 when the 2.54 eV excitation energy was used. The low-frequency Raman spectra reveal a series of shear and breathing modes (<50 cm−1) that are helpful for identifying the number of layers. The in-plane Eg and out-of-plane A1g modes of HfSe2 are located at ∼150 cm−1 and ∼200 cm−1, respectively. In HfS2, in-plane Eg and out-of-plane A1g optical phonons are observed at ∼260 cm−1 and ∼337 cm−1, respectively. The in-plane and out-of-plane force constants of atomically thin HfSe2 are obtained to be 1.87 × 1019N m−3 and 6.55 × 1019N m−3, respectively, by fitting the observed interlayer modes using the linear chain model. These results provide valuable information on materials parameters for device designs using atomically-thin layered HfX2 (X = S, Se).
期刊介绍:
2D Materials is a multidisciplinary, electronic-only journal devoted to publishing fundamental and applied research of the highest quality and impact covering all aspects of graphene and related two-dimensional materials.