High quality PdTe₂ thin films grown by molecular beam epitaxy

Abstract

PdTe 2 , a member of layered transition metal dichalcogenides (TMDs), has aroused significant research interest due to the coexistence of superconductivity and type-II Dirac fermions. It provides a promising platform to explore the interplay between superconducting quasiparticles and Dirac fermions. Moreover, PdTe 2 has also been used as a substrate for monolayer antimonene growth. Here in this paper, we report the epitaxial growth of high quality PdTe 2 films on bilayer graphene/SiC(0001) by molecular beam epitaxy (MBE). Atomically thin films are characterized by scanning tunneling microscopy (STM), X-ray photoemission spectroscopy (XPS), low-energy electron diffraction (LEED), and Raman spectroscopy. The band structure of 6-layer PdTe 2 film is measured by angle-resolved photoemission spectroscopy (ARPES). Moreover, our air exposure experiments show excellent chemical stability of epitaxial PdTe 2 film. High-quality PdTe 2 films provide opportunities to build antimonene/PdTe 2 heterostructure in ultrahigh vacuum for future applications in electronic and optoelectronic nanodevices.

Epitaxial growth of monolayer PdTe2 and patterned PtTe2 by direct tellurization of Pd and Pt surfaces

“…The high-resolution STM image (Figure 2c) demonstrates the atomic structures of PdTe2, which is hexagonal arrangements of Te atoms with an interatomic distance of 4.7 Å (Figure 2a and 2d). This number corresponds to (√3×√3) lattice of Pd(111) (√3×2.75=4.76 Å), which indicates an in-plane lattice expansion of the asgrown PdTe2 compared with bulk 19 due to lattice match during epitaxial growth. In the case of PtTe2, a monolayer film was obtained at low annealing temperature of 200 o C except for a few individual nanoparticles on the surface (Figure 2f).…”

“…After deposition at room temperature, the centroids of the Pd 3d5/2 and Pd 3d3/2 peaks are 335.6 eV and 340.9 eV, respectively, which shift towards higher binding energies (BEs) by 0.5 eV with respect to those of Pd(111) (Figure 3a (Figure 3b and 3d), which are higher by ~0.5 eV than those of bulk materials. 19,21 This could be attributed to charge transfer between the epitaxial grown monolayers and substrates due to differences in work functions. 32,33 The effect of annealing temperature was investigated.…”

“…However, unlike common TMDCs, both PdTe2 and PtTe2 show strong interlayer interaction due to their specific electronic configurations (nearly full occupation of d orbits and high hybridization of p orbits), 17,18 which makes it challenging to obtain ultrathin 2D layers through "top-down" methods such as mechanical exfoliation. Very recently, PdTe2 and PtTe2 few layer flakes have been grown by molecular beam epitaxy (MBE) and chemical vapor deposition (CVD), [19][20][21] demonstrating a promising "bottomup" approach to synthesize monolayers. More interestingly, in another studied NTMD, platinum diselenide (PtSe2), intrinsically patterned 1T/1H monolayer has been achieved during epitaxial growth by controlling concentration of defects, 22 indicating a potential way to create 2D patterns of NTMDs with designed defect arrangements.…”

Dirac semimetal PdTe2 temperature-dependent quasiparticle dynamics and electron–phonon coupling

“…At room temperature (300 K), two Raman shift modes values are ∼ 75.4 cm −1 and ∼ 133.2 cm −1 . These correspond, respectively, to Te atoms in-plane (E g ) and outof-plane (A 1g ) motions [46,51,52] respectively. These values are are consistent with previous reports bulk PdTe 2 values [52].…”

Novel two-dimensional transition metal chalcogenides created by epitaxial growth

“…More interestingly, bilayer PdSe 2 nanoribbon with a width of ~5 nm can be grown on top of the PdSe 2 islands (Figure 3(o)), giving the opportunity to explore the properties of 1D TMDs. Other TMDs like high quality PdTe 2 thin films with 1T phase [74] and TiTe 2 monolayer with 2H phase [75] have been fabricated through co-deposition by epitaxial growth. High-quality PdTe 2 films provide opportunities to build an antimonene/PdTe 2 heterostructure in ultra-high vacuum for future applications in electronic and optoelectronic nanodevices.…”