1. Effect of heteroepitaxial growth on LT-GaAs: ultrafast optical properties
- Author
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Horace Andrew Husay, Elizabeth Ann Prieto, Aizitiaili Abulikemu, Armando Somintac, Gerald Angelo Catindig, Arnel Salvador, Jessica Afalla, Karl Cedric Gonzales, Masahiko Tani, Muneaki Hase, and Elmer Estacio
- Subjects
Materials science ,Silicon ,Phonon ,chemistry.chemical_element ,FOS: Physical sciences ,02 engineering and technology ,Substrate (electronics) ,low temperature growth ,Epitaxy ,01 natural sciences ,Fluence ,Crystal ,terahertz ,Condensed Matter::Materials Science ,coherent phonon ,0103 physical sciences ,General Materials Science ,010306 general physics ,Spectroscopy ,Plasmon ,Condensed Matter - Materials Science ,Condensed matter physics ,Condensed Matter::Other ,GaAs ,Materials Science (cond-mat.mtrl-sci) ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,heteroepitaxy ,chemistry ,0210 nano-technology - Abstract
Epitaxial low temperature grown GaAs (LT-GaAs) on silicon (LT-GaAs/Si) has the potential for terahertz (THz) photoconductive antenna applications. However, crystalline, optical and electrical properties of heteroepitaxial grown LT-GaAs/Si can be very different from those grown on semi-insulating GaAs substrates (reference). In this study, we investigate optical properties of an epitaxial grown LT-GaAs/Si sample, compared to a reference grown under the same substrate temperature, and with the same layer thickness. Anti-phase domains and some crystal misorientation are present in the LT-GaAs/Si. From coherent phonon spectroscopy, the intrinsic carrier densities are estimated to be ~$10^{15}$ cm$^{-3}$ for either sample. Strong plasmon damping is also observed. Carrier dynamics, measured by time-resolved THz spectroscopy at high excitation fluence, reveals markedly different responses between samples. Below saturation, both samples exhibit the desired fast response. Under optical fluences $\geq$ 54 $\mu$ J/cm$^2$, the reference LT-GaAs layer shows saturation of electron trapping states leading to non-exponential behavior, but the LT-GaAs/Si maintains a double exponential decay. The difference is attributed to the formation of As-As and Ga-Ga bonds during the heteroepitaxial growth of LT-GaAs/Si, effectively leading to a much lower density of As-related electron traps., Comment: 8 pages, supplementary info separate
- Published
- 2021