The Raman spectra for single-walled carbon nanotubes (SWNTs) at different temperatures are studied. We find that the G peak position shifts to low frequency with increasing temperature. The variation rate of the peak frequency as a function of temperature is a factor of 2–3 larger than the corresponding values for multiwalled carbon nanotubes and highly ordered pyrolytic graphite from room temperature to 673 K. The line shapes of the radial breathing mode features are also found to be sensitive to temperature. Softening of the interatomic force constant due to thermal expansion of C–C bonds and relaxation of the weak van der Waals interaction between the SWNTs in a bundle with increasing temperature are suggested to be the main origins of the reversible spectral variations.

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Inserting a SiO2 layer underneath the p-pad electrode as the current blocking layer (CBL) structure and extending p-metal finger patterns, the GaN LEDs using an indium-tin-oxide (ITO) layer show the improved light output intensity, resulting from better current spreading and reduced light loss on the surface of p-pad metal. The LEDs with an oxide layer of 100 μm-pad-width and 6 μm-finger-width have better light output intensities than those with an oxide layer of 105 μm-pad-width and 12 μm-finger-width. Using the ATLAS device simulator from Silvaco Corporation, the current density distributions on the active layer in CBL LEDs have been investigated.

High-altitude electromagnetic pulse (HEMP) is generated from a nuclear burst at high altitudes above the Earth, the electromagnetic fields reach the ground nearly simultaneously with regard to the operation time of systems. The aim of this analysis is to inquire about HEMP characteristics and to analyze about effect in orthogonal frequency division multiplexing (OFDM) system. Specifically, HEMP characteristics are classified field sources, spatial coverage, time domain behavior, frequency spectrum and field intensities in this study. Bits error rate (BER) of the receiver with the software simulation is confirmed for the HEMP effect. Q-factor made a difference about interference duration by transfer characteristics of system. When Q factor is smaller, the recovery time from HEMP interference is short. To the contrary, if the Q factor is larger, the recovery duration is lasted longer by 300-600%.

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