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

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