Browsing by Author "Liu, Chun-Kuan"

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Effect of V/III Ratios on Surface Morphology in a GaSb Thin Film Grown on GaAs Substrate by MOCVD
(2014-01-01)
Hsiao, Chih-Jen
;
Liu, Chun-Kuan
;
Huynh, Sa-Hoang
;
Minh, Thien-Huu Ha
;
Yu, Hung-Wei
The epitaxial growth of GaSb thin film with different V/III ratios on high-lattice-mismatched GaAs (001) substrates by metal organic chemical vapor deposition (MOCVD) was investigated. Under optimal V/III ratio of 2.5, we found that there are many periodic 90 degrees interfacial misfit dislocation (IMF) arrays existing at the GaAs/GaSb interface. The surface roughness is about 3.6nm, 2.2nm, 3.8nm, respectively while different V/III ratios (1.25, 2.5, 5) were adopted. These results demonstrated that the hill-and valley structure on the surface of GaSb/GaAs heterostructure can be effectively improved, and formed smooth surface morphology.
Performance improvement of highly mismatched GaSb layers on GaAs by interfacial-treatment-assisted chemical vapor deposition
(2017-01)
Hsiao, Chih-Jen
;
Minh-Thien-Huu Ha
;
Liu, Chun-Kuan
;
Hong-Quan Nguyen
;
Yu, Hung-Wei
Strain-relieved GaSb quantum dots on GaAs can be achieved by either periodic interfacial misfit (IMF) or the conventional Stranski-Krastanov (SK) growth modes by changing the growth parameters. In this study, the Sb interfacial treatment was employed to improve the GaSb crystal quality including low defect density, smooth surface morphology, and high hole mobility. This technique yields two-dimensional (2D) islands with a height as low as 1.7 nm and width up to 190 nm in the IMF growth mode. In contrast to the interfacial treatments conventionally employed in the initial strain relaxation of GaSb/GaAs hererostructure, the Sb treatment promotes the formation of strong Ga-Sb bonds on the surface of the grown island, which effectively reduces the interfacial free energy and thus promotes the formation of 2D islands. With the Sb interfacial treatment, a high-relaxation 100-nm GaSb epilayer was grown on the GaAs substrate, the epilayers was strain relaxed and exhibited enhanced electrical properties with a high hole mobility of similar to 667 cm(2) V-1 s(-1) and with superior optical properties as evidenced by the photoluminescence B-line peak. The results of this study demonstrate an effective interfacial-treatment growth technique to relax the initial strain for the highly mismatched GaSb layers grown on a GaAs substrate.