Direct-Indirect GeSn Band Structure Formation by Laser Radiation: The Enhancement of Sn Solubility in Ge
Optics & Laser Technology 2020
Pāvels Onufrijevs, Patrik Ščajev, Artūrs Medvids, Mindaugas Andrulevicius, Saulius Nargelas, Tadas Malinauskas, Sandra Stanionytė, Martynas Skapas, Līga Orlova, Artūrs Plūdons, Michael Oehme, Klara Lyutovich, Erich Kasper, Joerg Schulze, Hung Hsiang Cheng

Low equilibrium solid solubility of Sn atoms in Ge (less than 1%) leads to limitations in application of this material for IR detectors and emitters. Providing of non-equilibrium conditions by powerful pulsed laser radiation can be successfully applied for enhancement of solubility of impurity atoms in the host material. Here we present laser-induced monotonous redistribution of Sn atoms in Ge, based on the thermogradient effect aiming overcoming equilibrium limitations in the solubility. We applied pulsed nanosecond laser radiation to epitaxial Ge0.96Sn0.04 layer grown on Si substrate to increase Sn atomic concentration up to 14% at the surface layer. As a result, indirect-direct graded bandgap GeSn structure was formed. The TEM/EDS cross-section analysis, X-ray photoelectron spectroscopy, Raman and UV reflection spectra confirmed the increase of Sn atomic content at the surface by order of magnitude. SEM and AFM imaging provided evident microstructure changes, while carrier lifetime changes, determined by differential transmittivity, were not observed, indicating that laser irradiation does not generate defects which reduce electronic quality of the material.

Atslēgas vārdi
GeSn, Solid solution, Thermogradient effect, Laser radiation, Carrier recombination

Onufrijevs, P., Ščajev, P., Medvids, A., Andrulevicius, M., Nargelas, S., Malinauskas, T., Stanionytė, S., Skapas, M., Grase, L., Plūdons, A., Oehme, M., Lyutovich, K., Kasper, E., Schulze, J., Cheng, H. Direct-Indirect GeSn Band Structure Formation by Laser Radiation: The Enhancement of Sn Solubility in Ge. Optics & Laser Technology, 2020, Vol. 128, Article number 106200. ISSN 0030-3992. Pieejams: doi:10.1016/j.optlastec.2020.106200

Publikācijas valoda
English (en)
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