Studies on the optical properties of bulk GaAsSb epilayers on GaAs
Date Issued
2007
Date
2007
Author(s)
Shyu, Jen-Yu
DOI
zh-TW
Abstract
In this thesis, we study the optical and structural properties of GaAsSb bulk layers grown on (100) and (111)B semi-insulating GaAs substrates by gas source molecular beam epitaxy. The Sb composition drops from 0.3 to 0.1 as the substrate temperature increases from 450 to 550°C, indicating that Sb has a higher incorporation rate at lower growth temperature. It is due to the differences between the sublimation and atomization energies of As and Sb. The (111)B GaAsSb epilayers show phase separation when the substrate temperature is lower than 550°C. Furthermore, the band-gap energy of the (111)B sample was found to be larger than that of the (100) sample from the photoluminescence and optical absorption measurements. The lower band-gap energy observed in the (100) sample is probably induced by the increase in the spontaneous ordering. We observed that the (100) samples grown at higher temperature have larger below band-gap absorption, indicating more significant compositional fluctuation. The band tail states absorption of (111)B samples was found much more stronger and broader than that of the (100) samples. It arises from fierce compositional disorder, which is supported by the high resolution XRD measurement.
Subjects
銻砷化鎵
GaAsSb
Type
thesis
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