Scanning tunneling microscopy study revealed a van der Waals C60, solid film with 13% room-temperature lattice expansion on the GaAs(001) 2×4 surface. The mechanism involves fundamental Coulomb interaction due to...Scanning tunneling microscopy study revealed a van der Waals C60, solid film with 13% room-temperature lattice expansion on the GaAs(001) 2×4 surface. The mechanism involves fundamental Coulomb interaction due to charge transfer from the GaAs substrate. Theoretical calculation determines the charge transfer to be 1.76 electrons per C60 molecule. Oriented at its (110) crystallo-graphic axis this film also distinguishes itself from those formed on all other semiconductor and metal substrates where only the low-energy (111) hexagonal packing of C60 molecules was developed. It is shown that this is due to the one-dimensional confinement effect of the anisotropic substrate, which may have the prospect of controlling crystal growth.展开更多
In situ angle-resolved photoemission spectroscopy(ARPES)and scanning tunneling spectroscopy(STS)have been used to study the electronic structure of Pb thin films grown on a Si(111)substrates.The experiments reveal tha...In situ angle-resolved photoemission spectroscopy(ARPES)and scanning tunneling spectroscopy(STS)have been used to study the electronic structure of Pb thin films grown on a Si(111)substrates.The experiments reveal that the electronic structure near the Fermi energy is dominated by a set of m-shaped subbands because of strong quantum confinement in the films,and the tops of the m-shaped subbands form an intriguing ring-like Van Hove singularity.Combined with theoretical calculations,we show that it is the Van Hove singularity that leads to an extremely high density of states near the Fermi energy and the recently reported strong oscillations(with a period of two monolayers)in various properties of Pb films.展开更多
文摘Scanning tunneling microscopy study revealed a van der Waals C60, solid film with 13% room-temperature lattice expansion on the GaAs(001) 2×4 surface. The mechanism involves fundamental Coulomb interaction due to charge transfer from the GaAs substrate. Theoretical calculation determines the charge transfer to be 1.76 electrons per C60 molecule. Oriented at its (110) crystallo-graphic axis this film also distinguishes itself from those formed on all other semiconductor and metal substrates where only the low-energy (111) hexagonal packing of C60 molecules was developed. It is shown that this is due to the one-dimensional confinement effect of the anisotropic substrate, which may have the prospect of controlling crystal growth.
基金The work was supported by the National Natural Science Foundation of China(NSFC)The Ministry of Science and Technology of People’s Republic of China(MOST).
文摘In situ angle-resolved photoemission spectroscopy(ARPES)and scanning tunneling spectroscopy(STS)have been used to study the electronic structure of Pb thin films grown on a Si(111)substrates.The experiments reveal that the electronic structure near the Fermi energy is dominated by a set of m-shaped subbands because of strong quantum confinement in the films,and the tops of the m-shaped subbands form an intriguing ring-like Van Hove singularity.Combined with theoretical calculations,we show that it is the Van Hove singularity that leads to an extremely high density of states near the Fermi energy and the recently reported strong oscillations(with a period of two monolayers)in various properties of Pb films.
