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Evidence for impact ionization in vanadium dioxide
Pump-probe optical spectroscopy was used to investigate proposed charge-carrier multiplication via impact ionization in the M1 insulating phase of VO2. By comparing the transient reflectivities of the film when pumped at less than and then more than twice the band-gap energy, we observed a larger ul...
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Published in: | Physical review. B 2016-10, Vol.94 (15), p.155129, Article 155129 |
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Main Authors: | , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Pump-probe optical spectroscopy was used to investigate proposed charge-carrier multiplication via impact ionization in the M1 insulating phase of VO2. By comparing the transient reflectivities of the film when pumped at less than and then more than twice the band-gap energy, we observed a larger ultrafast response with the higher energy pump color while the film was still transiently in the insulating phase. We additionally identified multiple time scales within the charge dynamics and analyzed how these changed when the pump and probe wavelengths were varied. This experiment provided evidence that a fast carrier multiplication process, i.e., impact ionization, acts efficiently in this prototypical strongly correlated insulator, as was recently predicted by theoretical calculations. |
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ISSN: | 2469-9950 2469-9969 |
DOI: | 10.1103/PhysRevB.94.155129 |