arXiv subjects

K. B. Chong

Publications and source records attributed to K. B. Chong.

3 recordsLinked to original sources

arXiv2003

Fractal Analysis On Internet Traffic Time Series

Fractal behavior and long-range dependence have been observed in tele-traffic measurement and characterization. In this paper we show results of application of the fractal analysis to internet traffic via various methods. Our result demonstrate that the internet traffic exhibits self-similarity. Time-scale analysis show to be an effective way to characterize the local irregularity. Based on the result of this study, these two Internet time series exhibit fractal characteristic with long-range dependence.

physics.comp-ph↗

arXiv2003

Improvement of dielectric loss of doped Ba0.5Sr0.5TiO3 thin films for tunable microwave devices

Al2O3-Ba0.5Sr0.5TiO3 (Al2O3-BST) thin films, with different Al2O3 contents, were deposited on (100) LaAlO3 substrate by pulsed laser deposition (PLD) technique. The Al2O3-BST films was demosnstrated to be a suitable systems to fabricate ferroelectric thin films with low dielectric loss and higher figure of merit for tunable microwave devices. Pure BST thin films were also fabricated for comparison purpose. The films' structure and morphology were analyzed by X-ray diffractiopn and scanning electron microscopy, respectively; nad showed that the surface roughness for the Al2O3-BST films increased with the Al2O3 content. Apart from that, the broadening in the intensity peak in XRD result indicating the grain size of the Al2O3-BST films reduced with the increasing of Al2O3 dopant. We measured the dielctric properties of Al2O3-BST films with a home-made non-destructive dual resonator method at frequency ~ 7.7 GHZ. The effect of doped Al2O3 into BST thin films significantly reduced the dielectric constant, dielectric loss and tunability compare to pure BST thin film. Our result shows the figure of merit (K), used to compare the films with varied dielectric properties, increased with the Al2O3 content. Therefore Al2O3-BST films show the potential to be exploited in tunable microwave devices.

cond-mat.mtrl-sci↗

arXiv2003

Pulsed Laser Deposition of LaAlO3-Ba0.5Sr0.5TiO3 Thin Films for Tunable Device Applications

LaAlO3-Ba0.5Sr0.5TiO3 (LAO-BST) thin films, with different LAO contents, were deposited on Pt/Ti/SiO2/Si and (100) LaAlO3 substrate, via a pulsed laser deposition (PLD). Phase composition and microstructure of the LAO-BST thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The LAO-BST thin films were solid solution of LAO nd BST, with lattice constant decreasing with increasing LAO content. The composition of (LAO)x(BST)1-x, estimated from the lattice constant of the thin films derived from the targets of 1/6, 2/6 and 3/6 LAO, was 0.143, 0.278, 0.476, respectively. The grain size of the thin films decreased as a result of the incorporation of LAO into BST. Dielectric properties of the LAO-BST thin films on Pt/Ti/SiO2/Si were measured at low frequency (100 kHz), while those on LaAlO3 substrate were characterized at high frequency (~7.9 GHz). The dielectric constants of the film derived from pure BST target and those from the targets with 1/6, 2/6 and 3/6 area ratio of LAO, on Pt/Ti/SiO2/Si substrate, were 772, 514, 395 and 282, with a dielectric loss of 0.096, 0.023, 0.024 and 0.025, and a dielectric tunability of 65%, 53%, 43% and 14%, respectively. The dielectric constant of the LAO-BST films on LaAlO3 substrate were 2436, 2148, 2018, 1805, with a maximum dielectric tunability of 11%, 13%, 10% and 8% at a maximum applied voltage of 2.4 kV (~9.2 kV/cm).

cond-mat.mtrl-sci↗