Anomalous phase relations of quantum size effects in ultrathin Pb films on Si(111)

Kim, Jisun; Zhang, Chendong; Kim, Jungdae; Gao, Hongjun; Chou, M. Y.; Shih, Chih‐Kang

doi:10.1103/physrevb.87.245432

Cited by 11 publications

(13 citation statements)

References 38 publications

(32 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[18][19][20][21] Pb islands usually exhibit a bilayer-to-bilayer growth mode on semiconductor substrates due to quantum size effect. [18][19][20][21][22][23][24] It is recently illustrated that Pb islands could be epitaxially grown on graphene and the interaction between Pb and C atoms is extremely weak. 12,14,15 In this work, low-temperature scanning tunneling microscopy (LT-STM) is adopted to study the growing status of Pb islands on G/SiC substrates.…”

Section: Introductionmentioning

confidence: 99%

Selective growth of Pb islands on graphene/SiC buffer layers

Liu

Miao

et al. 2015

Journal of Applied Physics

View full text Add to dashboard Cite

Graphene is fabricated by thermal decomposition of silicon carbide (SiC) and Pb islands are deposited by Pb flux in molecular beam epitaxy chamber. It is found that graphene domains and SiC buffer layer coexist. Selective growth of Pb islands on SiC buffer layer rather than on graphene domains is observed. It can be ascribed to the higher adsorption energy of Pb atoms on the 6 ffiffi ffi 3 p reconstruction of SiC. However, once Pb islands nucleate on graphene domains, they will grow very large owing to the lower diffusion barrier of Pb atoms on graphene. The results are consistent with first-principle calculations. Since Pb atoms on graphene are nearly free-standing, Pb islands grow in even-number mode. V

show abstract

Section: Introductionmentioning

confidence: 99%

Selective growth of Pb islands on graphene/SiC buffer layers

Liu

Miao

et al. 2015

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…12 ML and 13 ML are referred to as a cross-over region that is caused by a phase slip of the bilayer oscillations resulting from the accumulation of phase-matching errors. The details of the film stability and of the cross-over are well described in other studies [19,20]. The overall distribution of these islands with moiré pattern looks uniform on the surface, except for the thinnest region of the area circled in Fig.…”

Section: Resultsmentioning

confidence: 84%

“…Then, 0.2 ML Au was deposited on top of the Pb mesa islands at a low temperature (90 K) and the sample temperature was maintained below 110 K while transferring the sample to a STM stage. Annealing treatment of up to 250 K was conducted by placing the sample at room temperature stage and the residential time vs. the sample temperature was carefully calibrated [19]. The thickness of Pb film was referenced on the wetting layer of Si(111) 7 × 7 surfaces.…”

Section: Sample Preparationmentioning

confidence: 99%

“…The electronic confinement along the vertical direction leads to formation of quantum well states (QWS) in Pb thin film. Due to a half integer matching between Pb layer spacing along (111) planes and the Fermi wavelength, profound bilayer oscillations as a function of Pb thickness were reported with respect to various physical properties of the Pb films, such as stability [19][20][21][22], superconductivity [23,24], surface reactivity [25,26], and work function [27,28].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of quantum well states on the formation of Au–Pb alloy in ultra-thin Pb films

et al. 2015

Self Cite

View full text Add to dashboard Cite

“…2(a)). The bilayer oscillations of ϕ M are owing to the nearly half-integer phase matching between the Fermi wavelength and the lattice spacing along the (111) direction, which have been examined both theoretically [35,36] and experimentally [37,38]. Although our Si substrate has only 4 atomic layers, we checked that a thicker Si substrate does not modify the trend qualitatively.…”

Section: Introductionmentioning

confidence: 97%

The role of quantum confinement in the formation of Schottky barriers in Pb–Si interfaces

Chan

Souto-Casares

Chelikowsky

et al. 2015

Solid State Communications

View full text Add to dashboard Cite

a b s t r a c tSchottky barriers form when semiconductors are in contact with metal overlayers establishing a common Fermi level. Few theoretical studies of these materials exist as electronic structure calculations are computationally intensive for mismatched interfaces. We explicitly model a Pb(111) film on a Si (111) substrate. For thick Pb overlayers, we find a bulk regime where the Fermi level is pinned. For thin film regimes (less than five overlayers), structural relaxations dominate the interfacial energy as charge transfer is suppressed by quantum confinement. In this case, the Schottky barrier height follows the trend of the metal work function.One of the first models to predict the formation of a Schottky barrier is from Schottky [1,2] and Mott [3] some 70 years ago. The Schottky-Mott theory assumes that the metal and the semiconductor are not strongly interacting at the interface. Under such an assumption the vacuum levels are aligned, and the size of an ntype Schottky barrier Φ B;n ¼ ϕ M Àχ, which is the difference between the work function of the metal, ϕ M , and the electron affinity of the semiconductor, χ. If the Schottky-Mott picture was to be correct, then one might consider altering the barrier by changing the work function of the metal, e.g., by using different metals or by physically changing the thickness of the metal to alter the work function by quantum confinement. For some semiconductors, such as those with a wide band gap, Φ B;n exhibits an increasing trend with larger ϕ M ; however, the Fermi level E Fermi is often pinned within a small range for a given semiconductor regardless of the work function of the metal, especially for small gap semiconductors or elemental semiconductors like Si or Ge [4][5][6]. The Schottky-Mott model was rapidly abandoned for some semiconductor systems because of experimental evidence for a pinned Fermi level [7]. E Fermi when pinned is essentially independent of the metal contact. Bardeen [8] considered the role of surface states, whose theory had been previously developed by Matt [9] and Shockley [10], and argued that these states would control the formation of a dipole at the metal-semiconductor interface and pin E Fermi .Later, Heine [11] and Louie et al. [12,13] refined the ideas of Bardeen by noting that intrinsic surface states could not exist in the presence of an intimate contact with metallic states. They argued that the role played by the surface states pinning E Fermi in the Bardeen model could be played by the tails of intrinsic metallic states, which were capable of penetrating several layers into the semiconductor side. These metal induced gap states (MIGS) have been widely studied theoretically since the mid-1970s. For example, Louie and coworkers [12][13][14][15] used a jellium model for the metal films, replacing the nuclear charges by a uniform electronic charge density.The jellium model removes structural details of a metal overlayer and avoids the complexity of any lattice mismatch between the metal and semiconductor crystal structure...

show abstract

Anomalous phase relations of quantum size effects in ultrathin Pb films on Si(111)

Cited by 11 publications

References 38 publications

Selective growth of Pb islands on graphene/SiC buffer layers

Selective growth of Pb islands on graphene/SiC buffer layers

Influence of quantum well states on the formation of Au–Pb alloy in ultra-thin Pb films

The role of quantum confinement in the formation of Schottky barriers in Pb–Si interfaces

Contact Info

Product

Resources

About