27 research outputs found
Observations of conduction-band structure of 4H- and 6H-SiC
Ballistic electron-emission spectroscopy (BEES) and photoluminescence are used to study conduction-band structure related transport properties of the 4H and 6H polytypes of SiC. A secondary energy threshold at 2.7 eV is observed in the BEES spectrum of 4H-SiC, in good agreement with a value of 2.8 eV deduced from reported ab initio calculations. The results from 6H-SiC, are suggested to be influenced by transport properties of other polytype inclusions, also supported by band-edge transitions evident in 6H-SiC photoluminescence spectra
Confinement-enhanced electron transport across a metal-semiconductor interface
We present a combined scanning tunneling microscopy and ballistic electron emission microscopy study of electron transport across an epitaxial Pb/Si(111) interface. Experiments with a self-assembled Pb nanoscale wedge reveal the phenomenon of confinement-enhanced interfacial transport: a proportional increase of the electron injection rate into the semiconductor with the frequency of electron oscillations in the Pb quantum well
Imaging subsurface reflection phase with quantized electrons
Lead quantum wells (QW) epitaxially grown on annealed Pb/Si(111) interface form a model system for the study of interactions between quantized electrons and adiabatically modulated boundaries. Tunnel spectra of this system reveal a previously unknown adiabatic shift of QW resonances due to lateral variations of the electronic reflection phase at the buried interface. With this effect, lateral distribution of the subsurface reflection phase can be probed, using scanning tunneling microscopy
Anisotropic Metal-Insulator Transition in Epitaxial Thin Films
Quantum wells made of simple polyvalent metals represent a novel family of
doped 2D Mott-Hubbard insulators. As scanning tunneling microscopy experiments
show, these systems exhibit an anisotropic form of metal-insulator transition.
Their elementary excitations possess coherent wave-like properties along the
normal axis, and show an incoherent behavior in-plane. The development of such
an anisotropic coherence is most likely related to Coulomb interaction between
localized and delocalized thin film electronic states - 2D Kondo screening.Comment: 4 figures, submitted to PR
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Confinement-Enhanced Electron Transport across a Metal-Semiconductor Interface
We present a combined scanning tunneling microscopy and ballistic electron emission microscopy study of electron transport across an epitaxial Pb/Si(111) interface. Experiments with a self-assembled Pb nanoscale wedge reveal the phenomenon of confinement-enhanced interfacial transport: a proportional increase of the electron injection rate into the semiconductor with the frequency of electron oscillations in the Pb quantum well.Engineering and Applied SciencesOther Research Uni
Dual-probe scanning tunneling microscope for study of nanoscale metal-semiconductor interfaces
Using a dual-probe scanning tunneling microscope, we have performed three-terminal ballistic electron emission spectroscopy on Au/GaAs(100) by contacting the patterned metallic thin film with one tip and injecting ballistic electrons with another tip. The collector current spectra agree with a Monte-Carlo simulation based on modified planar tunneling theory. Our results suggest that it is possible to study nanoscale metal-semiconductor interfaces without the requirement of an externally-contacted continuous metal thin film