Direct-indirect GeSn band structure formation by laser Radiation: The enhancement of Sn solubility in Ge
| Autor: | Joerg Schulze, Saulius Nargelas, Hung Hsiang Cheng, Michael Oehme, Arturs Medvids, Martynas Skapas, Liga Grase, Erich Kasper, Mindaugas Andrulevičius, Pavels Onufrijevs, Klara Lyutovich, Sandra Stanionytė, Arturs Pludons, Patrik Ščajev, Tadas Malinauskas |
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| Rok vydání: | 2020 |
| Předmět: |
010302 applied physics
Materials science Band gap Analytical chemistry 02 engineering and technology Carrier lifetime 021001 nanoscience & nanotechnology Microstructure 01 natural sciences Atomic and Molecular Physics and Optics Electronic Optical and Magnetic Materials symbols.namesake X-ray photoelectron spectroscopy 0103 physical sciences symbols Irradiation Electrical and Electronic Engineering Solubility 0210 nano-technology Electronic band structure Raman spectroscopy |
| Zdroj: | Optics & Laser Technology. 128:106200 |
| ISSN: | 0030-3992 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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