Terahertz emission increase in GaAs films exhibiting structural defects grown on Si (100) substrates using a two-layered LTG-GaAs buffer system

Terahertz (THz) emission increase is observed for GaAs thin films that exhibit structural defects. The GaAs epilayers are grown by molecular beam epitaxy on exactly oriented Si (100) substrates at three different temperatures ( T s  = 320 °C, 520 °C and 630 °C). The growth method involves the deposi...

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Bibliographic Details
Published in:Journal of materials science. Materials in electronics 2021-05, Vol.32 (10), p.13825-13836
Main Authors: Gonzales, Karl Cedric, Prieto, Elizabeth Ann, Catindig, Gerald Angelo, De Los Reyes, Alexander, Faustino, Maria Angela, Tumanguil-Quitoras, Mae Agatha, Husay, Horace Andrew, Vasquez, John Daniel, Somintac, Armando, Estacio, Elmer, Salvador, Arnel
Format: Article
Language:English
Subjects:
Antiphase boundaries
Buffers
Characterization and Evaluation of Materials
Chemistry and Materials Science
Crystal defects
Crystal structure
Crystallinity
Electron diffraction
Emitters
Epitaxial growth
Excitation
Gallium arsenide
High energy electrons
Low temperature
Materials Science
Molecular beam epitaxy
Optical and Electronic Materials
Raman spectroscopy
Reflection
Silicon substrates
Spectrum analysis
Thin films
Threading dislocations
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Summary:Terahertz (THz) emission increase is observed for GaAs thin films that exhibit structural defects. The GaAs epilayers are grown by molecular beam epitaxy on exactly oriented Si (100) substrates at three different temperatures ( T s  = 320 °C, 520 °C and 630 °C). The growth method involves the deposition of two low-temperature-grown (LTG)-GaAs buffers with subsequent in-situ thermal annealing at T s  = 600 °C. Reflection high energy electron diffraction confirms the layer-by-layer growth mode of the GaAs on Si. X-ray diffraction shows the improvement in crystallinity as growth temperature is increased. The THz time-domain spectroscopy is performed in reflection and transmission excitation geometries. At T s  = 320 °C, the low crystallinity of GaAs on Si makes it an inferior THz emitter in reflection geometry, over a GaAs grown at the same temperature on a semi-insulating GaAs substrate. However, in transmission geometry, the GaAs on Si exhibits less absorption losses. At higher T s , the GaAs on Si thin films emerge as promising THz emitters despite the presence of antiphase boundaries and threading dislocations as identified from scanning electron microscopy and Raman spectroscopy. An intense THz emission in reflection and transmission excitation geometries is observed for the GaAs on Si grown at T s  = 520 °C, suggesting the existence of an optimal growth temperature for GaAs on Si at which the THz emission is most efficient in both excitation geometries. The results are significant in the growth design and fabrication of GaAs on Si material system intended for future THz photoconductive antenna emitter devices.
ISSN:0957-4522
1573-482X
DOI:10.1007/s10854-021-05958-8