Browsing by Author "Hsu, J. S."

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Photoluminescence studies of type-II diluted magnetic semiconductor ZnMnTe/ZnSe quantum dots
(2006-12-25)
Kuo, M. C.
;
Hsu, J. S.
;
Shen, J. L.
;
Chiu, K. C.
;
Fan, W. C.
Type-II diluted magnetic semiconductor ZnMnTe quantum dots (QDs) in ZnSe matrix grown by molecular beam epitaxy were investigated by conventional and magnetophotoluminescence (PL) spectroscopy. The QD emission exhibits a type-II characteristic in excitation power dependence of PL peak energy. A nonzero circular polarization of PL at the absence of magnetic field was observed. This phenomenon is attributed to the accumulation of interface charges confined in adjacent layers. The magneto-optical measurement demonstrates a magnetic-induced degree of circular polarization in the PL spectra, indicating the Mn incorporation into the QD system. (c) 2006 American Institute of Physics.
Pressure-induced metallization and resonant Raman scattering in Zn(1-x)Mn(x)Te
(2008-07-01)
Lin, Y. C.
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Fan, W. C.
;
Chiu, C. H.
;
Ke, F. K.
;
Yang, S. L.
Pressure-induced resonant Raman scattering is adopted to analyze the zone-center optical phonon modes and crystal characteristics of Zn(1-x)Mn(x)Te (0 <= x <= 0.26) thin films. The pressure (Pt) at which the semiconducting undergoes a transition to the metallic phase declines as a function of Mn concentration (x) according to the formula Pt(x)=15.7-25.4x+19.0x(2) (GPa). Pressure-dependent longitudinal and transverse optical phonon frequencies and the calculated mode Gruneisen parameters were adopted to investigate the influence of Mn(2+) ions on the iconicity. The experimental results indicate that the manganese ions tend to increase the iconicity of ZnTe under ambient conditions, whereas an external hydrostatic pressure tends to reduce the iconicity and the bond length of Zn(1-x)Mn(x)Te. (c) 2008 American Institute of Physics.
Temperature dependence of excitonic emission in cubic CdSe thin film
(2008-01-01)
Chia, C. H.
;
Yuan, C. T.
;
Ku, J. T.
;
Yang, S. L.
;
Chou, W. C.
A detailed photoluminescence investigation of the thermal redshift and broadening of the excitonic line of cubic CdSe film grown by molecular beam epitaxy is presented. Free excitonic emission from the cubic Use film was observed at low temperature. Temperature-dependent measurement was performed to obtain material parameters related to exciton-phonon interaction by fitting the experimental data to the phenomenological model. The relative contribution of both acoustic and optical phonon to the band gap shrinkage and exciton linewidth broadening are discussed. Exciton binding energy of 16 +/- 1.5 meV was determined from the Arrhenius analysis. (C) 2007 Elsevier B.V. All rights reserved.