Papers by Keyword: 1/f Noise

Abstract: Operation of SiC MOSFETs beyond 300°C opens up opportunities for a wide range of CMOS based digital and analogue applications. However the majority of the literature focuses only on the optimization of a single type of MOS device (either PMOS or more commonly NMOS) and there is a lack of a comprehensive study describing the challenge of optimizing CMOS devices. This study reports on the impact of gate oxide performance in channel implanted SiC on the electrical stability for both NMOS and PMOS capacitors and transistors. Parameters including interface state density (D_it), flatband voltage (V_FB), threshold voltage (V_TH) and effective charge (N_EFF) have been acquired from C-V characteristics to assess the effectiveness of the fabrication process in realising high quality gate dielectrics. The performance of SiC based CMOS transistors were analyzed by correlating the characteristics of the MOS interface properties, the MOSFET 1/f noise performance and transistor on-state stability at 300°C. The observed instability of PMOS devices is more significant than in equivalent NMOS devices. The results from MOS capacitors comprising interface state density (D_it), flatband voltage (V_FB), threshold voltage (V_TH) for both N and P MOS are in agreement with the expected characteristics of the respective transistors.

Abstract: The goal of this research is to model the drain current and 1/f noise degradation characteristics of n-channel MOSFETs. In this paper, we present the implementation of hot carrier degradation into drain current equations of BSIM4 model. We show simulation results of the DC drain current degradation, and then 1/f noise voltage density simulation results affected by the drain current degradation. We have extracted BSIM4 model parameters extensively with the measured data including I-V and 1/f noise measurement of our TEGs. Especially for 1/f noise degradation characterizations, the input referred noise has been calculated after extracting the 1/f noise parameter degradations.

Abstract: To ascertain physical mechanism of charge transport in Si/SiO_x structures with Ge nanoclusters the measurements of their DC and AC conductivity, and also the low-frequency measurements were performed. It was revealed that in the temperatures range 110 – 250 K the characteristics measured are governed by the hopping mechanism of charge transport. The model proposed suggests that the charge hopping becomes possible due to the band of localized states inducing in the bandgap of silicon substrate when Ge nanoclusters are introduced. The model was used to estimate some parameters of hopping transport. Also, the analysis of the low-frequency noise measured for Si/SiO_x structures with Ge nanoclusters allowed to ascertain the mechanism of charge hopping resulting in strong temperature dependence of the 1/f noise measured.

Abstract: Magnetic anomaly detection is a passive method for detection of a ferromagnetic target, and its performance is often limited by external noise with a power spectral density of 1/f ^a, (0<a<2). In consideration of this kind of noise is non-stationary, self-similarity and long-range correlation, an effective adaptive detection based on the wavelet transform is proposed in this paper. The discrete wavelet transform of the noisy signal is chosen as the inputs of the adaptive whitening filter, and then decomposed by the orthonormal basis functions (OBFs) and the energy signal was taken out for threshold detection. The simulation results show that the algorithm improves the effect for detecting weak magnetic anomaly signal contaminated by 1/f ^a noise.

Abstract: Low frequency noise in 4H-SiC lateral p-channel metal oxide semiconductor field effect transistors (PMOSFETs) in the frequency range from 1 Hz to 100 kHz has been used to investigate the relationship between gate dielectric fabrication techniques and the resulting density of interface traps at the semiconductor-dielectric interface in order to examine the impact on device performance. The results show that the low frequency noise characteristics in p-channel 4H-SiC MOSFETs in weak inversion are in agreement with the McWhorter model and are dominated by the interaction of channel carriers with interface traps at the gate dielectric/semiconductor interface.

Abstract: Magnetic anomaly detection is a passive method for detection of a ferromagnetic target, and its performance is often limited by external noise with a power spectral density of 1/f ^a, (0<a<2). In consideration of this kind of noise is non-stationary, self-similarity and long-range correlation, an effective noise reduction method based on the wavelet transform is proposed in this paper. The proposed method is only take one parameter into account, while the hard thresholding and soft thresholding methods utilize the relationship of the variance of the noisy signal. The simulation results show that the performance of our proposed method is superior to that of other methods.

Abstract: This study addresses a method for simulating a leaf dynamics on the basis of a 1/f noise method. Firstly, a 1/f noise with linear varying amplitude is used to simulate a selected leaf boundary detected and recognized. Secondly, a sample points operation is employed within its boundary after a corresponding reprocess is adopted, and then the corresponding body within its boundary is capable of being simulated. Finally, simulation for the leaf dynamics may be completed by using a dynamically rotating coordinates method. The experimental results show that this method has a better capability and can be used to realize simulation for the leaves with regular shapes to some extent.

Abstract: Low-frequency noise of the structures with Ge-nanoclusters of rather high surface density grown on the oxidized silicon surface is investigated for the first time. It was revealed that the 1/f ^γ noise, where γ is close to unity, is the typical noise component. Nevertheless, the 1/f ^γ noise sources were found to be distributed nonuniformly upon the oxidized silicon structure with Ge-nanoclusters. The noise features revealed were analyzed in the framework of widely used noise models. However, the models used appeared to be unsuitable to explain the noise behavior of the structures studied. The physical processes that should be allowed for to develop the appropriate noise model are discussed.

Abstract: This paper deals with excess noise sources in dielectric materials. We focus especially on the concrete samples that are frequently tested to ensure information about the reliability and level of degradation. Nevertheless, the testing methods are limited mainly by the proper contact creation, signal detection and noise defined sensitivity. Our efforts are directed to the noise properties assessment. It turns out that the Johnson-Nyquist noise and the 1/f (flicker) noise are generated in the different regions with the different response to the internal or external electric field. In addition the noise analysis is affected by the internal polarization phenomena and the material residual humidity. This issue in connection with the sample geometrical properties and the dielectric noise measurement methodology take part in this paper.

Abstract: In fact, the 1/f noise spectrum is correlated with the interface trap density of a MOSFET gate oxide, and the trap density generation in gate oxide is strong dependently on the hot-carrier injection. In this paper, we will investigate this phenomenon and compare with the threshold voltage shifted measured by the static I-V analysis. Eventually, it is found that the technique of the low frequency 1/f noise spectrum is an accurate and sensitive tool to detect the hot-carrier damage.