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Your search keyword '"Zhu, C.-F."' showing total 167 results
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167 results on '"Zhu, C.-F."'

14. Low-frequency noise in GaN thin films deposited by rf-plasma assisted molecular-beam epitaxy.

Author

Leung, B. H., Fong, W. K., Zhu, C. F., and Surya, Charles

Subjects
GALLIUM nitride, MOLECULAR beam epitaxy
Abstract

We report detailed investigations of low-frequency excess noise in GaN thin-film cross-bridge structures deposited by rf-plasma assisted molecular-beam epitaxy on top of an intermediate-temperature buffer layer (ITBL) grown at 690 °C. The experimental data indicates strong dependence of the voltage noise power spectra on the thickness of the ITBL with an optimal thickness of 800 nm. A model has been presented to account for the observed noise, which stipulates that the phenomenon arises from the thermally activated trapping and detrapping of carriers. The process results in the correlated fluctuations in both the carrier number and the Coulombic scattering rate. Detailed computation shows that number fluctuation dominates in our samples. Our numerical evaluation indicates a reduction in the trap density by over an order of magnitude with the use of an ITBL in the growth of GaN thin films. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2002
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37. Coupling Analysis of Liquid Sloshing and Structural Vibration Using General Software.

Author

Zhu, C. F., Tang, G. A., and Zhang, M. Y.

Subjects
SLOSHING (Hydrodynamics), STRUCTURAL dynamics, COMPUTER software, HEAT conduction, MODAL analysis
Abstract

In this paper, a convenient modal analysis method for the linear coupled vibration of a container that is partially filled with a fluid is introduced. This problem is important for various reasons, such as stability analysis. The fluid-structure interactions in an elastic tank with an incompressible liquid are assumed to produce small vibrations. Reduced symmetric finite element equations of the system are acquired according to the component mode synthesis method. Considering that the liquid satisfies the same governing equation as steady heat conduction, general programs can be used to calculate the mass matrix and stiffness matrix of the coupled system. Then, modal analysis of the liquid container using general software, e.g., MSC Nastran, that ensures accuracy and stableness in the process, is applied to demonstrate that this method can determine the modal frequency in a fluid-structure coupled system. [ABSTRACT FROM AUTHOR]

Published
2015
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42. Low-frequency Noise Characterization of Hot-electron Degradation in GaN-based HEMTs.

Author

Jha, S., Gao, J., Zhu, C. F., Jelenkovic, E., Tong, K. Y., Pilkuhn, M., Surya, C., and Schweizer, H.

Subjects
MODULATION-doped field-effect transistors, FIELD-effect transistors, PARTICLES (Nuclear physics), SPECTRAL energy distribution, SPECTRUM analysis, PHYSICS
Abstract

Hot-electron degradation in MOCVD-grown GaN-based HEMTs, with different gate recess depths, was monitored by flicker noise measurement. Drastic changes were observed in the flicker noise power spectral density, SV(f) and I-V characteristics when the devices were subjected to voltage stress at VD=10V for a short stress time of tS=1 minute. The degradations can be partially reverted by annealing the devices at 100°C for 20 minutes. Further stressing of the devices were performed with VG=-1.5V and VD=10V, which results in irreversible degradation in the SV(f). Detailed analyses of the data suggest that the stressing of the devices, with short tS, results in the generation of H+ at the AlGaN/GaN interface leading to the observed increase in ID, and SV(f). This can be easily annealed as the H+ has relatively low formation energy. The experimental results suggest that the H+ accumulated at the AlGaN/GaN interface may result in a network of percolation paths formed by the depression of the surface potential at the heterointerface. Motion of the H+, arising from the application of a large VD, leads to the modulation of the percolation paths of the carriers in the 2DEG resulting in large random fluctuations in SV(f). Further stressing of the devices exhibit substantial increase in SV(f) due to the generation of traps at the AlGaN/GaN interface. The experimental results demonstrate the significant impact of gate recess depths on the lifetimes of the devices. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2005
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