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-e...

Full description

Saved in:
Bibliographic Details
Published in:Applied physics letters 2014-07, Vol.105 (4)
Main Authors: Sakamoto, Tetsuya, Hayashi, Shuhei, Yasutake, Yuhsuke, Fukatsu, Susumu
Format: Article
Language:English
Subjects:
ABSORPTION
Applied physics
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
EFFICIENCY
ELECTRON BEAM INJECTION
ELECTRONS
EXCITATION
GERMANIUM
HOLES
LASER RADIATION
OPTICAL PUMPING
PHONONS
RELAXATION
SEMICONDUCTOR MATERIALS
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4891755