F. Martinez

Impact of Random Telegraph Signal in CMOS Image Sensors for Low-Light Levels

This paper presents the investigation of fluctuating pixels resulting from the random telegraph signal (R.T.S) of the source-follower transistor. The work takes into account the impact of the source-follower noise power spectral density (P.S.D) dispersion through correlated double sampling (C.D.S) readout circuit used in CMOS active pixel image sensors. The results allow the determination of the output r.m.s noise versus R.T.S noise characteristics. The distinctiveness of the observed flickering pixels is discussed in detail and the proposed mechanisms behind the phenomena are viewed in light of the collected data. We show that R.T.S noise main parameters dispersion of the source-follower transistor is a major factor influencing the circuit output r.m.s noise value distribution in a pixel array. Results are compared with experimental data

Floating-Body SOI Memory: The Scaling Tournament

In this paper, we present an overview of the typical device architectures of the single transistor capacitorless dynamic random access memory (1T-DRAM). This memory uses only one transistor and takes advantage of floating body effects in SOI and SOI-like devices. The principles of operation and key mechanisms for programming are described. The various approaches are compared in terms of architecture, performance and potential for aggressive scaling.

Impact of gate current noise on drain current noise in 90 nm CMOS technology

Gate and drain current noises on a 90 nm CMOS technology are investigated. Gate current noise shows 1/f and white noise. White noise is very close to shot noise, and we have a quadratic variation of 1/f noise with gate current. Coherence measurements show that the increase of drain noise at high gate biases can be attributed to tunneling effects.

Numerical modeling of low frequency noise in ultrathin oxide MOSFETs

We present a numerical low frequency noise modeling related to oxide trapping/detrapping process, based on green’s function formulation and its application to ultrathin oxide characterization. This model allows slow trap density profiles to be determined. The model was applied in the investigation of the validity of the flat band voltage fluctuation model in the case of thin oxides. Numerical gate current noise modeling was applied to the characterization of nitridation‐induced traps. Finally, 2D model was applied in the investigation of low‐frequency degradation of MOSFETs stressed by hot‐carriers, and the generated slow oxide trap density profiles were deduced.

Thickness characterization by capacitance derivative in FDSOI p-i-n gated diodes

The SOI structural characterization is addressed in this paper by using split capacitance measurements on p-i-n gated diodes. The p+ and n+ contacts supply promptly electrons and holes in the body, preventing the diode from the parasitic transient effects that undermine the capacitance measurements in SOI MOSFETs. A novel method to determine the silicon film thickness, based on the capacitance derivative, is presented and validated by experiments and TCAD simulations.

1/f noise, transport and percolation in carbon nanotube film field‐effect transistors: simulation and experiments

In this paper we present a model for electrical properties of carbon nanotube film field‐effect transistors. The model, based on carbon nanotube physics uses Landauer formalism and tight binding calculation. The total film is described as an electrical network. A modified nodal analysis provides DC and noise characteristics. Theses simulations are in good agreements with experimental results.

1/f noise in strained SiGe on Insulator MOSFETs

This paper presents low-frequency noise in Si<inf>0.75</inf>Ge<inf>0.25</inf> and Si<inf>0.65</inf>Ge<inf>0.35</inf> p- and n-channel strained Germanium on Insulator (SGOI) MOSFETs with 15nm thick substrates and with TiN/HfO<inf>2</inf>/SiO<inf>2</inf> gate stacks, obtained using the enrichment technique. In strong inversion, front and back interface current noise in PMOSFET devices is described using the ΔN model, whereas NMOSFET noise is described using the ΔN-Δµ model, with a ten-fold increase in noise in some cases. In weak inversion, the noise behavior deviates from these standard models and may be described by noise coupling between the two interfaces. For both types of device, the extracted densities are approximately the same, with no significant impact from the variation of the Ge content.

Comparison of the effects of different surfactants on electrical parameters in Carbon Nanotube thin films

In this paper, we present a study of 2-D Carbon Nanotubes “CNTs” thin film. Transport and noise fluctuation of two types of films are measured and compared. We have developed a theoretical model based on CNT physics, where the films are described as an electrical network. Simulations using a Modified Nodal Analysis “MNA” provide DC and noise characteristics comparable to the experimental results.

Interface oxide trap characterisation in germanium-on-insulator 0.12 μm PMOS transistors by drain current noise measurements

This paper presents an experimental analysis of the noise measurements performed in germanium on insulator (GeOI) 0.12 μm PMOS transistors. The front gate stack is composed of a SiO2/HfO2 material with a TiN metal gate electrode. The result is an aggressively reduced equivalent oxide thickness (EOT) of 1.8 nm. The buried oxide is used as a back gate for experimental purposes. Front gate and back gate oxides/Ge interfaces are characterized. The slow oxide trap densities of the two interfaces are extracted. The values obtained for the front gate oxide are N<inf>t</inf>(E<inf>Fn</inf>) = 1.2 10¹⁸ cm⁻³ eV⁻¹ and are comparable to values for nitrided oxides on Si bulk. The extracted values for slow oxide trap densities of the SiO<inf>2</inf>/Ge interface are between 6 and 8 1017 cm⁻³ eV⁻¹ and are close to those of state of art buried oxide SiO<inf>2</inf>/Si interfaces. These results are of importance for the future development of GeOI technologies.

Low Frequency Noise of Ultrathin Oxide MOSFETs using Green’s Function Approach

In this paper, we present a new numerical model of the flat band voltage power spectral density (SVFB) in ultra‐thin gate oxides. Unlike previous classical models, we don’t use the equivalent concept which relates the fluctuation of the oxide charge to the flat‐band voltage fluctuation. Localized noise sources in the oxide are implanted into the model and by using a Green’s function approach, the spectral cross‐correlation of the electrical potential is evaluated at each node in the device mesh in order to obtain a highly accurate physical description. In the paper, we evaluate the validity of the classical model. In view of this, we have compared simulation results to those of the classical formulation, in the case of thin oxides.