Browsing by Author "Wang, Kai-Wei"

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Improved 1.3-mu m Electroluminescence of InGaAs-Capped Type-II GaSb/GaAs Quantum Rings at Room Temperature
(2013-01-01)
Lin, Wei-Hsun
;
Wang, Kai-Wei
;
Lin, Shih-Yen
;
Wu, Meng-Chyi
;
光電學院
Room-temperature 1.3-mu m electroluminescence is observed for the InGaAs-capped GaSb quantum rings (QRs). The increasing carrier density in the InGaAs-capped type-II GaSb QRs would induce a larger blue shift in the same laser pumping power span and enhance the luminescence intensity. The enhanced luminescence intensity, a larger blue shift of peak wavelength, and 1.3-mu m emission of the InGaAs-capped QR structure have revealed its potential application in multi-wavelength light-emitting devices in the near infrared range.
Long-wavelength electroluminescence of InGaAs-capped type-II GaSb/GaAs quantum-rings at room temperature
(2013-09-01)
Lin, Wei-Hsun
;
Wang, Kai-Wei
;
Lin, Shih-Yen
;
Wu, Meng-Chyi
;
光電學院
The room-temperature photoluminescence (PL) and electroluminescence (EL) exceeding 1.3 mu m are observed for InGaAs-capped GaSb quantum-ring (QR) structures. With increasing In composition, the emission wavelength would shift from 1.18 to 131 mu m. The InGaAs-capped GaSb QRs also exhibit a higher injection current and stronger EL intensity at the same applied voltage. With the observation of low-temperature PL spectra, the transition mechanisms of the standard and InGaAs-capped QRs are further investigated. (c) 2012 Elsevier B.V. All rights reserved.
Temperature-dependent photoluminescence and carrier dynamics of standard and coupled type-II GaSb/GaAs quantum rings
(2013-09-01)
Lin, Wei-Hsun
;
Wang, Kai-Wei
;
Lin, Shih-Yen
;
Wu, Meng-Chyi
;
光電學院
Temperature-dependent photoluminescence (PL) and the corresponding carrier dynamics of standard and coupled type-II GaSb/GaAs quantum rings (QRs) are investigated in this article. Compared with standard QRs, the slower PL intensity decay of coupled QRs with increasing temperature is attributed to the depression of thermal quenching. More intense PL intensity is also observed for the coupled-QR sample at room temperature. With further reducing the GaAs spacer layer thickness to 2 nm, near two-times PL enhancement is observed. The results indicate that with the enhanced luminescence intensity of coupled-QR structure, type-II nano-structures may be utilized for light-emitting device applications. (c) 2013 Elsevier B.V. All rights reserved.
The formation mechanisms and optical characteristics of GaSb quantum rings
(2013-08-07)
Lin, Wei-Hsun
;
Wang, Kai-Wei
;
Liao, Yu-An
;
Pao, Chun-Wei
;
Lin, Shih-Yen
The growth mechanisms and optical characteristics of GaSb quantum rings (QRs) are investigated. Although As-for-Sb exchange is the mechanism responsible for the dot-to-ring transition, significant height difference between GaSb quantum dots (QDs) and QRs in a dot/ring mixture sample suggests that the dot-to-ring transition is not a spontaneous procedure. Instead, it is a rapid transition procedure as long as it initiates. A model is established to explain this phenomenon. Larger ring inner diameters and heights of the sample with longer post Sb soaking time suggest that As-for-Sb exchange takes places in both vertical and lateral directions. The decreasing ring densities, enlarged ring inner/outer diameters and eventually flat GaSb surfaces observed with increasing growth temperatures are resulted from enhanced adatom migration and As-for-Sb exchange with increasing growth temperatures. (C) 2013 AIP Publishing LLC.
Type-II GaSb/GaAs coupled quantum rings: Room-temperature luminescence enhancement and recombination lifetime elongation for device applications
(1970-01-01)
Lin, Wei-Hsun
;
Wang, Kai-Wei
;
Chang, Shu-Wei
;
Shih, Min-Hsiung
;
Lin, Shih-Yen
Type-II GaSb/GaAs coupled quantum rings have exhibited two-order-of-magnitude luminescence enhancement and ten-times elongation of recombination lifetime at room temperature as compared with regular rings. The longer lifetime suggests that a significant amount of electrons are confined in coupled rings rather than simply leaking away. These phenomena indicate that type-II nanostructures can be potentially utilized for room-temperature luminescence and carrier storage applications. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4737443]