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Title: An alternative route for efficient optical indirect-gap excitation in Ge

Abstract

We explored optical excitation pathways in the multivalley semiconductor Ge in an attempt to expedite selective electron injection into the indirect L-band-edge. An off-peak resonant excitation route was developed, which offers the pumping efficiency outperforming the phonon-assisted near-indirect-edge absorption by more than six orders of magnitude. The valley selectivity results from the intra-valley relaxation that separates electrons and holes in momentum space following excitation. Fortuitously, the widely used green laser, 532 nm, is found to be nearly ideally suited to the efficient L-valley-selective excitation in Ge. Such valley-specific pumping may help clarify the otherwise complicated electron dynamics involving intervalley processes.

Authors:
; ;  [1];  [1];  [2]
  1. Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902 (Japan)
  2. (Japan)
Publication Date:
OSTI Identifier:
22311194
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; EFFICIENCY; ELECTRON BEAM INJECTION; ELECTRONS; EXCITATION; GERMANIUM; HOLES; LASER RADIATION; OPTICAL PUMPING; PHONONS; RELAXATION; SEMICONDUCTOR MATERIALS

Citation Formats

Sakamoto, Tetsuya, Hayashi, Shuhei, Fukatsu, Susumu, E-mail: cfkatz@mail.ecc.u-tokyo.ac.jp, Yasutake, Yuhsuke, and PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012. An alternative route for efficient optical indirect-gap excitation in Ge. United States: N. p., 2014. Web. doi:10.1063/1.4891755.
Sakamoto, Tetsuya, Hayashi, Shuhei, Fukatsu, Susumu, E-mail: cfkatz@mail.ecc.u-tokyo.ac.jp, Yasutake, Yuhsuke, & PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012. An alternative route for efficient optical indirect-gap excitation in Ge. United States. doi:10.1063/1.4891755.
Sakamoto, Tetsuya, Hayashi, Shuhei, Fukatsu, Susumu, E-mail: cfkatz@mail.ecc.u-tokyo.ac.jp, Yasutake, Yuhsuke, and PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012. Mon . "An alternative route for efficient optical indirect-gap excitation in Ge". United States. doi:10.1063/1.4891755.
@article{osti_22311194,
title = {An alternative route for efficient optical indirect-gap excitation in Ge},
author = {Sakamoto, Tetsuya and Hayashi, Shuhei and Fukatsu, Susumu, E-mail: cfkatz@mail.ecc.u-tokyo.ac.jp and Yasutake, Yuhsuke and PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012},
abstractNote = {We explored optical excitation pathways in the multivalley semiconductor Ge in an attempt to expedite selective electron injection into the indirect L-band-edge. An off-peak resonant excitation route was developed, which offers the pumping efficiency outperforming the phonon-assisted near-indirect-edge absorption by more than six orders of magnitude. The valley selectivity results from the intra-valley relaxation that separates electrons and holes in momentum space following excitation. Fortuitously, the widely used green laser, 532 nm, is found to be nearly ideally suited to the efficient L-valley-selective excitation in Ge. Such valley-specific pumping may help clarify the otherwise complicated electron dynamics involving intervalley processes.},
doi = {10.1063/1.4891755},
journal = {Applied Physics Letters},
number = 4,
volume = 105,
place = {United States},
year = {Mon Jul 28 00:00:00 EDT 2014},
month = {Mon Jul 28 00:00:00 EDT 2014}
}