| Autor: |
Gassenq, A., Tardif, S., Guilloy, K., Duchemin, I., Pauc, N., Hartmann, J. M., Rouchon, D., Widiez, J., Niquet, Y. M., Milord, L., Zabel, T., Sigg, H., Faist, J., Chelnokov, A., Rieutord, F., Reboud, V., Calvo, V. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 2017, Vol. 121 Issue 5, p1-8, 8p, 1 Diagram, 2 Charts, 5 Graphs |
| Abstrakt: |
The application of high values of strain to Ge considerably improves its light emission properties and can even turn it into a direct band gap semiconductor. Raman spectroscopy is routinely used for strain measurements. Typical Raman-strain relationships that are used for Ge were defined up to ~1% strain using phonon deformation potential theory. In this work, we have studied this relationship at higher strain levels by calculating and measuring the Raman spectral shift-strain relations in several different strain configurations. Since differences were shown between the usual phonon deformation potential theory and ab-initio calculations, we highlight the need for experimental calibrations. We have then measured the strain in highly strained Ge micro-bridges and micro-crosses using Raman spectroscopy performed in tandem with synchrotron based micro-diffraction. High values of strain are reported, which enable the calibration of the Raman-strain relations up to 1.8% of in plane strain for the (001) biaxial stress, 4.8% strain along 〈100〉, and 3.8% strain along 〈110〉. For Ge micro-bridges, oriented along 〈100〉, the nonlinearity of the Raman shift-strain relation is confirmed. For the 〈110〉 orientation, we have shown that an unexpected non-linearity in the Raman-strain relationship has also to be taken into account for high stress induction. This work demonstrates an unprecedented level of strain measurement for the 〈110〉 uniaxial stress and gives a better understanding of the Raman-strain relations in Ge. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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