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Proceedings Paper

Direct probing of local-density-of-states in semiconductor nanostructures
Author(s): Kiyoshi Kanisawa; Yasuhiro Tokura; Hiroshi Yamaguchi; Yoshiro Hirayama
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Paper Abstract

The electronic features of semiconductor nanostructures, such as zero-dimensional states, are usually inferred from macroscopic optical and transport experiments. Although, direct probing of electrical features in semiconductor nanostructures looks very attractive, it is very difficult for a conventional semiconductor structure. However, direct probing becomes possible through a combination of low-temperature scanning tunneling microscopy and InAs(111)A surface in an ultra-high vacuum, where conductive electrons automatically accumulate near the clean surface. The clear observation of a Friedel oscillation pattern around a dislocation demonstrates successful mapping of the local-density-of-states (LDOS) of the conductive electrons. Inverted pyramidal defects are naturally formed during molecular beam epitaxial growth of InAs thin films on GaAs(111)A substrates and they operate as well-defined quantum dots. The measured LDOS pattern inside the quantum dots clearly changes as a function of energy, i.e. a sample bias, reflecting the LDOS pattern of each zero-dimensional state. A resonant concentration of the LDOS to the zero-dimensional energy levels is also demonstrated in these experiments. The LDOS measurements of a series of inverted pyramidal quantum dots with different side lengths and their comparison with theoretical calculations suggest a unique feature of the quantum dot system examined in this study.

Paper Details

Date Published: 1 July 2003
PDF: 8 pages
Proc. SPIE 4999, Quantum Sensing: Evolution and Revolution from Past to Future, (1 July 2003); doi: 10.1117/12.479607
Show Author Affiliations
Kiyoshi Kanisawa, NTT Corp. (Japan)
Yasuhiro Tokura, NTT Corp. (Japan)
Hiroshi Yamaguchi, NTT Corp. (Japan)
Yoshiro Hirayama, NTT Corp. (Japan)

Published in SPIE Proceedings Vol. 4999:
Quantum Sensing: Evolution and Revolution from Past to Future
Manijeh Razeghi; Gail J. Brown, Editor(s)

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