Chih-Hung Chen

Bio: Chih-Hung Chen is an academic researcher from McMaster University. The author has contributed to research in topics: Flicker noise & Noise (electronics). The author has an hindex of 26, co-authored 102 publications receiving 2354 citations. Previous affiliations of Chih-Hung Chen include Chang Gung University & Simon Fraser University.

An effective gate resistance model for CMOS RF and noise modeling

Abstract: A physics-based effective gate resistance model representing the non-quasi-static (NQS) effect and the distributed gate electrode resistance is proposed for accurately predicting the RF performance of CMOS devices. The accuracy of the model is validated with 2D simulations and experimental data. In addition, the effect of the gate resistance on the device noise behavior has been studied with measured data. The result shows that an accurate gate resistance model is essential for the noise modeling.

Channel noise modeling of deep submicron MOSFETs

Abstract: This brief presents a new channel noise model using the channel length modulation (CLM) effect to calculate the channel noise of deep submicron MOSFETs. Based on the new channel noise model, the simulated noise spectral densities of the devices fabricated in a 0.18 /spl mu/m CMOS process as a function of channel length and bias condition are compared to the channel noise directly extracted from RF noise measurements. In addition, the hot electron effect and the noise contributed from the velocity saturation region are discussed.

MOSFET modeling for RF IC design

Abstract: High-frequency (HF) modeling of MOSFETs for radio-frequency (RF) integrated circuit (IC) design is discussed Modeling of the intrinsic device and the extrinsic components is discussed by accounting for important physical effects at both dc and HF The concepts of equivalent circuits representing both intrinsic and extrinsic components in a MOSFET are analyzed to obtain a physics-based RF model The procedures of the HF model parameter extraction are also developed A subcircuit RF model based on the discussed approaches can be developed with good model accuracy Further, noise modeling is discussed by analyzing the theoretical and experimental results in HF noise modeling Analytical calculation of the noise sources has been discussed to understand the noise characteristics, including induced gate noise The distortion behavior of MOSFET and modeling are also discussed The fact that a MOSFET has much higher "low-frequency limit" is useful for designers and modelers to validate the distortion of a MOSFET model for RF application An RF model could well predict the distortion behavior of MOSFETs if it can accurately describe both dc and ac small-signal characteristics with proper parameter extraction

Extraction of the induced gate noise, channel noise, and their correlation in submicron MOSFETs from RF noise measurements

Abstract: An extraction method to obtain the induced gate noise (i~/sub g/~/sup 2/~) channel noise (i~/sub d/~/sup 2/~), and their cross correlation (i~/sub g/~i~/sub d/~*~) in submicron MOSFETs directly from scattering and RF noise measurements has been presented and verified by measurements. In addition, the extracted induced gate noise, channel noise, and their correlation in MOSFETs fabricated in 0.18-/spl mu/m CMOS process versus frequencies, bias conditions, and channel lengths are presented and discussed.

Approaching the Schottky-Mott limit in van der Waals metal-semiconductor junctions.

Abstract: The junctions formed at the contact between metallic electrodes and semiconductor materials are crucial components of electronic and optoelectronic devices 1 . Metal-semiconductor junctions are characterized by an energy barrier known as the Schottky barrier, whose height can, in the ideal case, be predicted by the Schottky-Mott rule2-4 on the basis of the relative alignment of energy levels. Such ideal physics has rarely been experimentally realized, however, because of the inevitable chemical disorder and Fermi-level pinning at typical metal-semiconductor interfaces2,5-12. Here we report the creation of van der Waals metal-semiconductor junctions in which atomically flat metal thin films are laminated onto two-dimensional semiconductors without direct chemical bonding, creating an interface that is essentially free from chemical disorder and Fermi-level pinning. The Schottky barrier height, which approaches the Schottky-Mott limit, is dictated by the work function of the metal and is thus highly tunable. By transferring metal films (silver or platinum) with a work function that matches the conduction band or valence band edges of molybdenum sulfide, we achieve transistors with a two-terminal electron mobility at room temperature of 260 centimetres squared per volt per second and a hole mobility of 175 centimetres squared per volt per second. Furthermore, by using asymmetric contact pairs with different work functions, we demonstrate a silver/molybdenum sulfide/platinum photodiode with an open-circuit voltage of 1.02 volts. Our study not only experimentally validates the fundamental limit of ideal metal-semiconductor junctions but also defines a highly efficient and damage-free strategy for metal integration that could be used in high-performance electronics and optoelectronics.

Semiconductor Gas Sensors: Dry Synthesis and Application

Abstract: Since the development of the first chemoresistive metal oxide based gas sensors, transducers with innovative properties have been prepared by a variety of wet- and dry-deposition methods. Among these, direct assembly of nanostructured films from the gas phase promises simple fabrication and control and with the appropriate synthesis and deposition methods nm to μm thick films, can be prepared. Dense structures are achieved by tuning chemical or vapor deposition methods whereas particulate films are obtained by deposition of airborne, mono- or polydisperse, aggregated or agglomerated nanoparticles. Innovative materials in non-equilibrium or sub-stoichiometric states are captured by rapid cooling during their synthesis. This Review presents some of the most common chemical and vapor-deposition methods for the synthesis of semiconductor metal oxide based detectors for chemical gas sensors. In addition, the synthesis of highly porous films by novel aerosol methods is discussed. A direct comparison of structural and chemical properties with sensing performance is given.

IEEE Transactions on Microwave Theory and Techniques and Antennas and Propagation Announce a Joint Special Issue on Ultra-Wideband (UWB) Technology

Abstract: Before the emergence of ultra-wideband (UWB) radios, widely used wireless communications were based on sinusoidal carriers, and impulse technologies were employed only in specific applications (e.g. radar). In 2002, the Federal Communication Commission (FCC) allowed unlicensed operation between 3.1–10.6 GHz for UWB communication, using a wideband signal format with a low EIRP level (−41.3dBm/MHz). UWB communication systems then emerged as an alternative to narrowband systems and significant effort in this area has been invested at the regulatory, commercial, and research levels.