Overlapping effects of the optical transitions of GaNAs thin films grown by molecular beam epitaxy
| Autor: | José Ángel Espinoza-Figueroa, C.A. Mercado-Ornelas, C. M. Yee-Rendón, Ángel Rodríguez, I.E. Cortes-Mestizo, F.E. Perea-Parrales, L.I. Espinosa-Vega, Víctor Hugo Méndez-García, Luis Zamora-Peredo |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
02 engineering and technology Nitride 01 natural sciences Gallium arsenide Condensed Matter::Materials Science chemistry.chemical_compound Ellipsometry 0103 physical sciences Materials Chemistry Thin film Spectroscopy Electronic band structure 010302 applied physics business.industry Metals and Alloys Surfaces and Interfaces 021001 nanoscience & nanotechnology Surfaces Coatings and Films Electronic Optical and Magnetic Materials Semiconductor chemistry Optoelectronics 0210 nano-technology business Molecular beam epitaxy |
| Zdroj: | Thin Solid Films. 702:137969 |
| ISSN: | 0040-6090 |
| DOI: | 10.1016/j.tsf.2020.137969 |
| Popis: | Photoreflectance and ellipsometry are two very useful optical spectroscopy techniques employed to analyze the electronic band structure of semiconductors. Photoreflectance and ellipsometry spectra of gallium arsenide nitride (GaNAs) thin films on gallium arsenide (GaAs) layers may be composed of transitions from the conduction bands of the alloy and the binary (E-, E+, and E0, respectively) in conjunction with their interaction spin-orbit split-off valence band (E-+Δ0 and E0+Δ0). For low concentration of nitrogen (between 0.2 and 0.6 %), the determination of the E+ conduction band becomes difficult to distinguish by the fact that critical points are superimposed in the spectrum of both characterization techniques. In this work, a method to determine the E+ conduction band of GaNAs thin films grown on GaAs by molecular beam epitaxy is proposed when the overlapping of spectral features influences their optical determination. When using spectroscopic characterization techniques, the modulation/excitation region depends on the wavelength employed and sample characteristics, and consequently low nitrogen concentration in the alloy in conjunction with the thickness of the GaNAs layers have been found responsible for the signal overlapping. It is demonstrated that by decreasing the sample temperature in the photoreflectance process the overlapping is avoided, allowing for a correct interpretation of the GaNAs conduction band splitting analysis and discarding the contribution of built-in electric fields. From these results, we achieved a precise experimental determination of the presence/absence of the band splitting predicted by the band anti-crossing model using non-destructive characterization tools. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect