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

Authors :
Shuhei Hayashi
Yuhsuke Yasutake
Tetsuya Sakamoto
Susumu Fukatsu
Source :
Applied Physics Letters. 105:042101
Publication Year :
2014
Publisher :
AIP Publishing, 2014.

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.

Details

ISSN :
10773118 and 00036951
Volume :
105
Database :
OpenAIRE
Journal :
Applied Physics Letters
Accession number :
edsair.doi...........2bd50bfa1d9eef41ce06675b1941da26
Full Text :
https://doi.org/10.1063/1.4891755