Light-induced metal-insulator transition inSrTiO3by photoresistance spectroscopy
| Autor: | G. Bridoux, Carlos A. Figueroa, N. Bachi, Silvia P. Heluani, J. M. Ferreyra, M. Villafuerte |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Physical Review B. 92 |
| ISSN: | 1550-235X 1098-0121 |
| DOI: | 10.1103/physrevb.92.155202 |
| Popis: | Photoresistivity and its spectral response has been systematically studied in oxygen-deficient ${\mathrm{SrTiO}}_{3}$ single crystals for a wide range of resistivities $\ensuremath{\rho}$ and carrier densities $n$. At room temperature we found a persistent photoresistance that gradually decreases as $\ensuremath{\rho}$ is diminished or $n$ is increased, in addition to relaxation times of seconds to a few minutes, suggesting that trapping of carriers is playing a major role. An analysis of the photoresistance excitation spectra showed two distinctive features that are related to the indirect gap of ${\mathrm{SrTiO}}_{3}$ at $(3.25\ifmmode\pm\else\textpm\fi{}0.04)\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$ and to a direct transition at $(3.40\ifmmode\pm\else\textpm\fi{}0.03)\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$. The photoresistive crystals present a temperature-dependent resistivity under illumination that experiences a metal-insulator transition below $T\ensuremath{\sim}85\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The low-temperature photoresistance spectrum reveals a suitable technique to understand the origin of this transition, pointing to an enhanced efficiency of the $\ensuremath{\sim}3.25\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ gap to promote electrons to the bottom of the conduction band. |
| Databáze: | OpenAIRE |
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