Browsing by Author "Wu, Shung-Yi"

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Influence of As on the Morphologies and Optical Characteristics of GaSb/GaAs Quantum Dots
(2011-03-01)
Tseng, Chi-Che
;
Mai, Shu-Cheng
;
Lin, Wei-Hsun
;
Wu, Shung-Yi
;
Yu, Bang-Ying
The influence of As atoms on the morphologies of GaSb quantum dots (QDs) is investigated. Without any special treatment, GaSb quantum rings (QRs) are observed in the embedded GaSb layer even when the uncapped layer reveals QD-like morphologies. With intentional As supply after the uncapped GaSb QD deposition, a QD to QR transition is observed. The phenomenon suggests that insufficient Sb atoms on the GaSb QDs would lead to the QD to QR transition as in the case of embedded GaSb layers. With extended Sb soaking time following GaSb deposition, QD structures could be well maintained for the embedded GaSb layers. A light-emitting diode operated at room temperature is fabricated based on the GaSb/GaAs QD structure. Identical peak positions in photoluminescence and electroluminescence (EL) spectra of the device show that type-II GaSb QDs are responsible for the observed EL.
Room-Temperature Electro-Luminescence of Type-II GaSb/GaAs Quantum Rings
(2012-07-15)
Lin, Wei-Hsun
;
Lin, Meng-Yu
;
Wu, Shung-Yi
;
Lin, Shih-Yen
;
光電工程學系
The influence of Sb/background As flux ratios on GaSb nano-structures is investigated in this letter. With decreasing Sb/background As flux ratios under high Sb irradiation during the post soaking procedure, ring formation, photoluminescence (PL) intensity enhancement, and PL peak red shift are observed. With further reduced Sb flux and Sb/background As ratios, the observed more intense PL intensities of the quantum-ring (QR) samples compared with quantum dots suggest that more electron-hole wave function overlapping is obtained. The observation of room-temperature electro-luminescence of a QR PIN diode has revealed the potential of the nano-structure in light-emitting device application.
Room-temperature operation type-II GaSb/GaAs quantum-dot infrared light-emitting diode
(2010-03-22)
Lin, Shih-Yen
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Tseng, Chi-Che
;
Lin, Wei-Hsun
;
Mai, Shu-Cheng
;
Wu, Shung-Yi
A GaSb/GaAs quantum-dot light-emitting diode (QD LED) with a single GaSb QD layer is investigated in this paper. The room-temperature photoluminescence peak blueshift with increasing excitation power densities suggests a type-II alignment of the GaSb/GaAs heterostructures. Significant electroluminescence (EL) is observed for the device under forward biases, which suggests that pronounced dipole transitions occur at the GaSb/GaAs interfaces. With increasing forward biases, the observed EL peak blueshift confirms that the origin of luminescence is from the type-II GaSb/GaAs QD structures. A model is established to explain the operation mechanisms of the type-II QD LED.
The influence of background As on GaSb/GaAs quantum dots and its application in infrared photodetectors
(2012)
Lin, Wei-Hsun
;
Tseng, Chi-Che
;
Wu, Shung-Yi
;
Wu, Meng-Hsun
;
Lin, Shih-Yen
In this paper, GaSb nanostructures prepared under different Sb/background As ratios are investigated. With decreasing Sb/background As ratios, the morphologies of GaSb nanostructure changing from quantum dots (QDs) to quantum rings (QRs) are observed. The higher optical recombination probabilities of GaSb QRs are attributed to enhanced electron-hole wave function overlapping and more surrounding electrons around the GaSb QR core shell. With well-control Sb/background As ratios, the high-temperature operation GaSb quantum-dot infrared photodetector (QDIP) with simple stacked structure has been demonstrated. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
The transition mechanisms of type-II GaSb/GaAs quantum-dot infrared light-emitting diodes
(2011-05-15)
Tseng, Chi-Che
;
Lin, Wei-Hsun
;
Wu, Shung-Yi
;
Chen, Shu-Han
;
Lin, Shih-Yen
The light-emitting diode (LED) with a single GaSb QD layer embedded in a GaAs n-i-p structure operated under different injection currents and temperatures is investigated. With increase in injection currents, room-temperature electroluminescence (EL) peak blue shift is observed until a saturation of EL intensity is reached. In the temperature-varying EL measurements, with increase in temperatures. EL peak blue shift and then red shift are observed, which is attributed to the enhanced luminescence of the smaller QDs with increase in temperatures lower than 100 K. The understanding of the operation mechanisms for the device is advantageous for the practical application of type-II LEDs. (C) 2010 Elsevier B.V. All rights reserved.