Browsing by Author "Yang, Cheng-Hong"

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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
Electron Emission Properties of Nitrogen-Induced Localized Defects in InAsN/GaAs Quantum Dots
(2011-11-01)
Yang, Cheng-Hong
;
Hsieh, Meng-Chien
;
Wu, Chia-Wei
;
Chang, Yen-Ting
;
Wu, Yue-Han
The electron-emission properties of nitrogen-induced (N-induced) localized defects in InAsN/GaAs quantum dots (QDs) are investigated in detail by capacitance-voltage (C-V) profiling and bias-dependent deep-level transient spectroscopy (DLTS). The incorporation of nitrogen (N) into InAs QDs is shown to produce localized defects near QDs and threading-dislocation-related defects in the top GaAs layer. The threading dislocation is associated with an electron-emission energy of approximately 0.648 eV and emission from the sample surface toward the QDs. The electron-emission energy from the QDs associated with the localized defects increases from 0.19 to 0.36 eV, indicating that both types of defect near QDs have low electron emission energies. Therefore, the change in emission energy is attributable to the defects across the QD interface where a band offset exists. The C-V profile at 300 K shows extended carrier depletion near the QDs. As ac frequency increases, an electron-emission peak emerges at the QDs; this peak is followed by another prominent peak, suggesting that the localized defect that is responsible for this latter peak has an energy below the QD electron ground state. On the basis of a C-V profile simulation, this defect is located at the QD at the observed emission energy below the GaAs conduction band, 360 meV. A comparison with InAsN QD and strain relaxation InAs QD samples reveals that the localized defect arises from a nitrogen alloy fluctuation in the QD. The energy location of this defect reveals a possibility that incorporated N is associated with a particular mode. (C) 2011 The Japan Society of Applied Physics
Photoluminescence Study of Interdot Carrier Transfer on Strain-relaxed InAs Quantum Dots
(2011)
Chiang, Chen-Hao
;
Chang, You-Cheng
;
Wu, Yue-Han
;
Hsieh, Meng-Chien
;
Yang, Cheng-Hong
Photoluminescence (PL) properties of the strain relaxed InAs quantum dots (QDs) are studied as a function of temperature from 10 to 300 K. Two groups of QDs induced by strain relaxation are observed in the PL spectra. The PL peak position of the relaxed (non-relaxed) QDs locates at a higher (lower) energy. TEM image prove QDs are distributed into two groups and indicate the QDs relax the strain by diffusing indium to GaAs. In the 120- 200 K temperature range, there are abnormal temperature behaviors attributed to the carrier transfer from the relaxed to non-relaxed QDs.
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]
The Combinational Polymorphisms of ORAI1 Gene Are Associated with Preventive Models of Breast Cancer in the Taiwanese
(2015-01-01)
Fu Ou-Yang
;
Lin, Yu-Da
;
Chuang, Li-Yeh
;
Chang, Hsueh-Wei
;
Yang, Cheng-Hong
The ORAI calcium release-activated calcium modulator 1 (ORAI1) has been proven to be an important gene for breast cancer progression and metastasis. However, the protective association model between the single nucleotide polymorphisms (SNPs) of ORAI1 gene was not investigated. Based on a published data set of 345 female breast cancer patients and 290 female controls, we used a particle swarm optimization (PSO) algorithm to identify the possible protective models of breast cancer association in terms of the SNPs of ORAI1 gene. Results showed that the PSO-generated models of 2-SNP (rs12320939-TT/rs12313273-CC), 3-SNP (rs12320939-TT/rs12313273-CC/rs712853-(TT/TC)), 4-SNP (rs12320939-TT/rs12313273-CC/rs7135617-(GG/GT)/rs712853-(TT/TC)), and 5-SNP (rs12320939-TT/rs12313273-CC/rs7135617-(GG/GT)/rs6486795-CC/rs712853-(TT/TC)) displayed lowvalues of odds ratios (0.409-0.425) for breast cancer association. Taken together, these results suggested that our proposed PSO strategy is powerful to identify the combinational SNPs of rs12320939, rs12313273, rs7135617, rs6486795, and rs712853 of ORAI1 gene with a strongly protective association in breast cancer.