Browsing by Author "Chen, Y. J."

Now showing 1 - 9 of 9

A CMOS-Compatible, High RF Power, Asymmetric-LDD MOSFET with Excellent Linearity
(2008)
Chang, T.
;
Kao, H. L.
;
Chen, Y. J.
;
Liu, S. L.
;
McAlister, S. P.
We report the performance of 0.18 mu m RF power MOSFETs with an Asymmetric-Lightly-Doped-Drain (LDD) design. Such devices do not have an n-type drain extension and exhibited better characteristics than conventional MOSFETs at same gate length. The devices showed a DC breakdown voltage of 6.9 V, a 0.54 W/mm power density, 115 GHz f(max), and a good adjacent channel power ratio (ACPR) linearity, as well as a 52% drain efficiency at 2.4 GHz.
Cell Endurance Prediction from a Large-area SONOS Capacitor
(2009)
Lee, C. H.
;
Tu, W. H.
;
Gu, S. H.
;
Wu, C. W.
;
Lin, S. W.
Endurance considerations induced by the degadation of top and bottom oxides are proposed for a SONOS memory. First, a correlation is found between the widespread C-V curves induced by interface generation and cycling numbers (cyc. #). Unlike V-FB (accumulation region), V-T (inversion region) shows a much severe shift. Inter-face state (N-it) is identified as a key factor even when a 2nm bottom oxide is used. Moreover, charge to breakdown (Q(BD)) for an ONO capacitor under positive and negative constant current stress (CCS) is investigated. Our study reveals that QBD of such stacks strongly depends on the top oxide thickness. A field enhancement induced by charges in a trapping nitride layer is the root cause. Based on Weibull statistics, the risk of dielectric breakdown for both blocking layers is then evaluated.
Characterization study of GaN-based epitaxial layer and light-emitting diode on nature-patterned sapphire substrate
(2012-03-01)
Lin, H. Y.
;
Chen, Y. J.
;
Chang, C. L.
;
Li, X. F.
;
Kuo, C. H.
Chemical wet etching on c-plane sapphire wafers by three etching solutions (H3PO4, H2SO4, and H3PO4/H2SO4 mixing solution) was studied. Among these etching agents, the mixing H3PO4/H2SO4 solution has the fastest etching rate (1.5 mu m/min). Interestingly, we found that H2SO4 does not etch the c-plane sapphire wafer in thickness; instead, a facet pyramidal pattern is formed on the c-plane sapphire wafer. GaN light-emitting diode (LED) epitaxial structure was grown on the sapphire wafer with the pyramidal pattern and the standard flat sapphire wafer. X-ray diffraction and photoluminescence measurement show that the pyramidal pattern on the sapphire wafer improved crystalline quality but augmented the compressive stress level in the GaN LED epilayer. The horizontal LED chips fabricated on the pyramidal-patterned sapphire wafer have a larger light output than the horizontal LED chips fabricated on the standard flat sapphire wafer by 20%.
Improved Radio Frequency Power Characteristics of Complementary Metal-Oxide-Semiconductor-Compatible Asymmetric-Lightly-Doped-Drain Metal-Oxide-Semiconductor Transistor
(2010)
Chang, Tsu
;
Kao, Hsuan-Ling
;
Chen, Y. J.
;
Chin, Albert
;
電子工程學系及電子研究所
We have characterized and modeled the radio frequency (RF) power performance of a 0.18 mu m asymmetric-lightly-doped-drain metal-oxide-semiconductor field-effect transistor (LDD MOSFET). In comparison with the conventional 0.18 mu m MOSFET, this asymmetric-LDD device shows a larger power density of 0.54 W/mm, and 8 dB better adjacent channel power ratio (ACPR) linearity at 2.4 GHz from the improved twice DC breakdown voltage of 6.9 V. These significant improvements of RF power performance in the asymmetric-LDD transistor are important for the medium RF power amplifier application. (C) 2010 The Japan Society of Applied Physics
Overall Operation Considerations for a SONOS-based Memory
(2009)
Lee, C. H.
;
Tu, W. H.
;
Chong, L. H.
;
Gu, S. H.
;
Chen, K. F.
Erase characteristics of a SONOS-based structure are emulated not only for n(+)-poly and p(+)-poly gates but also for TaN-gate+Al2O3 combination. By incorporating our previous studies, performances including program, erase, and read disturb can be reviewed for both SONOS and TANOS devices. Unsurprisingly, it is hard to satisfy all requirements by using a SONOS device. In a TANOS device, an optimal bottom oxide thickness can be specified with the consideration of the three factors simultaneously. Moreover, it is found that conventional extrapolation methodology is inadequate to predict the lifetime of a TANOS device and tends to under-estimate the tolerable read bias.
Super-high Density Si Quantum Dot Thin Film for Photovoltaic Properties Enhancement
(2013)
Kuo, K. Y.
;
Huang, P. R.
;
Chen, Y. J.
;
Lee, P. T.
;
光電工程學系
A gradient Si-rich oxide multilayer deposition structure is proposed to achieve super-high density Si quantum dot (QD) thin film while preserving QD size control ability for better photovoltaic properties.
Synthesis of ethanol-soluble few-layer graphene nanosheets for flexible and transparent conducting composite films
(2011-07-22)
Nguyen, D. D.
;
Tai, N. H.
;
Chueh, Y. L.
;
Chen, S. Y.
;
Chen, Y. J.
We report a facile method of preparing few-layer graphene nanosheets (FLGs), which can be soluble in ethanol. Atomic force microscopy and high-resolution transmission electron microscopy studies reveal that FLGs have average thicknesses in the range of 2.6-2.8 nm, corresponding to 8-9 layers. A graphene/nafion composite film has a sheet resistance of 9.70 k Omega/sq at the transmittance of 74.5% (at 550 nm) while the nafion film on polyethylene terephthalate has a sheet resistance of 128 k Omega/sq at transmittance of 90.0%. For the cycling/bending test, almost no change in resistance was exhibited when the film was bent at an angle up to 140 degrees, and no obvious deviation in resistance could be found after 100 bending cycles was applied. In addition, an FLGs-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) composite layer was demonstrated as the effective hole transporting layer to improve the hole transporting ability in an organic photovoltaic device, with which the power conversion efficiency was enhanced from 3.10% to 3.70%. The results demonstrated the promising applications of FLGs on graphene-based electronics, such as transparent electrode and flexible conducting film.
Ultrafast optical probes of polaron dynamics in La(0.7)Ca(0.3)MnO(3) thin films
(2009-02-15)
Wu, K. H.
;
Hsu, T. Y.
;
Shih, H. C.
;
Chen, Y. J.
;
Luo, C. W.
In this work, we use ultrafast optical pump-optical probe spectroscopy to probe the polaron dynamics in La(0.7)Ca(0.3)MnO(3) (LCMO) thin films. The temporal evolution in transient reflectivity change Delta R/R exhibits two relaxing components: a fast component with a time constant of subpicosecond and a slow component with time constant ranging from tens of picoseconds to hundreds of picoseconds. The amplitude of the fast component, though has been seldom discussed before, exhibits the similar temperature dependence with that of the resistivity and the neutron scattering intensity due to nanoscale correlated polarons. The results strongly suggest that the fast photoinduced reflectivity change may have been due to the photoexcitation and trapping process of correlated Jahn-Teller polarons in the paramagnetic and ferromagnetic phases and, thus, implies the presence of electronic inhomogeneity in LCMO manganites.
Ultrafast optical probes of polaron dynamics in La0.7Ca0.3MnO3 thin films
(2009-02-15)
Wu, K. H.
;
Hsu, T. Y.
;
Shih, H. C.
;
Chen, Y. J.
;
Luo, C. W.
In this work, we use ultrafast optical pump-optical probe spectroscopy to probe the polaron dynamics in La0.7Ca0.3MnO3 (LCMO) thin films. The temporal evolution in transient reflectivity change Delta R/R exhibits two relaxing components: a fast component with a time constant of subpicosecond and a slow component with time constant ranging from tens of picoseconds to hundreds of picoseconds. The amplitude of the fast component, though has been seldom discussed before, exhibits the similar temperature dependence with that of the resistivity and the neutron scattering intensity due to nanoscale correlated polarons. The results strongly suggest that the fast photoinduced reflectivity change may have been due to the photoexcitation and trapping process of correlated Jahn-Teller polarons in the paramagnetic and ferromagnetic phases and, thus, implies the presence of electronic inhomogeneity in LCMO manganites.