Browsing by Author "Wang, Yu-Shou"

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Electron Emission Properties of GaAsN/GaAs Quantum Well Containing N-Related Localized States: The Influence of Illuminance
(2012-02-01)
Hsieh, Meng-Chien
;
Wang, Jia-Feng
;
Wang, Yu-Shou
;
Yang, Cheng-Hong
;
Chiang, Chen-Hao
This study elucidates the electron emission properties of GaAsN/GaAs quantum well containing N-related localized states under illumination. The N-related localized states in a GaAsN quantum well (QW) are identified as both optical and electrical electron trap states. The mechanisms for the responses of current-voltage (I-V) measurement under illumination and photocapacitance are investigated. N-related localized states in GaAsN QW can extend response range and response sensitivity on photocapacitance, and produce an additional current path for photo-generated electron-hole pairs. Furthermore, exactly how illumination influences the electron emission rate of GaAsN QW electron state is examined. The electron emission rate of GaAsN QW electron state can be modulated by different incident photon energy, which is due to the modulation of depletion width of the bottom GaAs. (C) 2012 The Japan Society of Applied Physics
Optical joint density of states in InGaN/GaN-based multiple-quantum-well light-emitting diodes
(2011-11-15)
Wang, Yu-Shou
;
Chen, Nai-Chuan
;
Lu, Chun-Yi
;
Chen, Jenn-Fang
;
電子物理學系
The optical joint densities of states of three InGaN/GaN-based light-emitting diodes with different emission wavelengths (violet, blue and green) operated at various currents were investigated. The results indicate that the blueshift of the emission with increasing current is related to the variation in optical joint density of states. Thus, the blueshift is ascribed to the screening of the piezoelectric field by carriers. A tail at the low-energy end of the density of states, corresponding to localized states, was found, and the presence of these tails broadens the spectra of the devices. (C) 2011 Elsevier B.V. All rights reserved.
Role of the N-related localized states in the electron emission properties of a GaAsN quantum well
(2011-11-15)
Hsieh, Meng-Chien
;
Wang, Jia-Feng
;
Wang, Yu-Shou
;
Yang, Cheng-Hong
;
Chen, Ross C. C.
This study elucidates the influence of the N-related localized states on electron emission properties of a GaAsN quantum well (QW) that is grown by molecular beam epitaxy. The N-related localized states in a GaAsN QW are identified as both optical and electrical electron trap states. Furthermore, exactly how N-related localized states influence the electron emission properties of a GaAsN quantum well is examined. The presence of N-related localized states effectively suppresses the tunneling emission of GaAsN QW electron states, leading to a long electron emission time for the GaAsN QW electron states. Thermal annealing can reduce the number of N-related localized states, resulting in a recovery of the tunneling emission for GaAsN QW electron states. Increasing the annealing temperature can restore the electron emission behavior of GaAsN QW to the typical electron tunneling emission for a high-quality QW. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3663436]