Browsing by Author "Lee, S. C."

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Deep-level emissions in GaAsN/GaAs structures grown by metal organic chemical vapor deposition
(2007-06-15)
Chen, J. F.
;
Ke, C. T.
;
Hsieh, P. C.
;
Chiang, C. H.
;
Lee, W. I.
This work presents the deep-level photoluminescence of coherently strained GaAsN/GaAs quantum-well (QW) structures with various GaAsN thicknesses and N contents. A broad deep-level emission at similar to 1.1 eV is observed, whose wavelength is redshifted as the GaAsN thickness increases. Based on its energy separation from the QW emission, this emission is attributed to a transition between the QW electron ground state and a deep level at similar to 0.2 eV above the GaAsN valence-band (VB) edge. This level is shown to be tied to the GaAs band edge. A transition between this level and the GaAs conduction band allows the GaAsN-GaAs band alignment to be evaluated. A type II band lineup is obtained with VB offsets of 0.03 and 0.002 eV for N=0.6% and 1.8%, respectively. The decreased VB offset suggests a transition from type II to type I with increasing N content. Thermal annealing effectively removes this level and improves the QW emission. The concentration of this level is not clearly correlated with N content, suggesting that this level is induced by a low-temperature growth of the GaAsN layer to suppress the composition fluctuation. Given its energy, this level is tentatively assigned to V-Ga. (c) 2007 American Institute of Physics.
Field Dependence of Porous Low-k Dielectric Breakdown as Revealed by the Effects of Line Edge Roughness on Failure Distributions
(2011-03-01)
Lee, S. C.
;
Oates, A. S.
;
Chang, K. M.
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We investigate the electric field (E) dependence of the breakdown of porous low-k dielectrics by measuring the changes in the failure time distribution resulting from the presence of line edge roughness. We show that the Weibull beta increases with decreasing field, clearly demonstrating that dielectric breakdown does not exhibit 1/E or E(-n) characteristics.