Abstract
We probe here the optical relaxation properties of Mg-doped wide-band-gap single crystals with both a high spectral and temporal resolution at cryogenic temperatures. Surprisingly, we observe the photoluminescence to decay in a two-step process: a fast relaxation and a slower one centered around an energy = 2.62 eV. Both decays fit well to the stretched-exponential behavior. Moreover, we are able to associate these energies to the recombination of light-induced and small polarons. Also, we checked the stability of our findings by using single crystals that show on-purpose modified radiative recombination processes, i.e., with a Mg doping both above and below the optical damage resistance threshold, as well as with different poling histories of inverted domains.
6 More- Received 14 January 2016
- Revised 5 April 2016
DOI:https://doi.org/10.1103/PhysRevB.93.174116
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