Dimensionality-Mediated Semimetal-Semiconductor Transition in Ultrathin <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>PtTe</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> Films
Meng-Kai Lin, Rovi Angelo B. Villaos, Joseph A. Hlevyack, Peng Chen, Ro-Ya Liu, Chia-Hsiu Hsu, J. Ávila, Sung‐Kwan Mo, Feng‐Chuan Chuang, T.‐C. Chiang
Abstract
Platinum ditelluride (PtTe_{2}), a type-II Dirac semimetal, remains semimetallic in ultrathin films down to just two triatomic layers (TLs) with a negative gap of -0.36 eV. Further reduction of the film thickness to a single TL induces a Lifshitz electronic transition to a semiconductor with a large positive gap of +0.79 eV. This transition is evidenced by experimental band structure mapping of films prepared by layer-resolved molecular beam epitaxy, and by comparing the data to first-principles calculations using a hybrid functional. The results demonstrate a novel electronic transition at the two-dimensional limit through film thickness control.