Correlation between most 1/f noise and CCD transfer inefficiency

The 1/f noise in MOS transistors has been investigated and is shown to correlate with charge transfer inefficiency experiments on surface-channel CCDs. Both independent phenomena can be quantitatively explained by the same interface state model. The oxide trap density turns out to vary by more than a factor 10. The 1/f noise is compared with McWhorter's number fluctuation model and with the mobility fluctuation model. The oxide trap density is calculated from the charge transfer inefficiency in surface CCDs. Both the quantitative agreement between oxide trap density and 1/f noise and the observed dependence of 1/f noise on gate voltage here give strong arguments in favour of the McWhorter model. The investigated MOS transistors fall into a category that cannot be explained by the present mobility fluctuation model

Empirical temperature dependence of the refractive index of semiconductors

Values of the temperature coefficient of the refractive index were obtained from the derivation of a simple relation between energy band-gap and refractive index in semiconductors. These values, (dn/dT)/n, were compared to the experimental data found in literature. Our model, with only one fitting parameter dB/dT=2.5×10-5 K-1 for all semiconductors, results in the best agreement with experimental data

Separation of random telegraph signals from 1/f noise in MOSFETs under constant and switched bias conditions

The low-frequency noise power spectrum of small dimension MOSFETs is dominated by Lorentzians arising from random telegraph signals (RTS). The low-frequency noise is observed to decrease when the devices are periodically switched 'off'. The technique of determining the statistical lifetimes and amplitudes of the RTS by fitting the signal level histogram of the time-domain record to two-Gaussian histograms has been reported in the literature. This procedure is then used for analysing the 'noisy' RTS along with the device background noise, which turned out to be 1/f noise. The 1/f noise of the device can then be separated from the RTS using this procedure. In this work, RTS observed in MOSFETs, under both constant and switched biased conditions, have been investigated in the time domain, Further, the 1/f noise in both the constant and the switched biased conditions is investigated

Noise in DMOS transistors in a BICMOS-technology

An experimental and theoretical study of the 1/f noise and the thermal noise in double-diffused MOS (DMOS) transistors in a BICMOS-technology has been carried out. By using an analytical model that consists of an enhancement MOS transistor in series with a depletion MOS transistor and a resistance, and by attributing noise sources to each device, the noise in DMOS devices is simulated accurately. Three distinct regions of operation are defined: enhancement transistor control, depletion transistor control and the linear region. In the first region, the noise is strictly determined by the enhancement transistor. It was found that the 1/f noise in this region is caused by mobility fluctuations and is very low. In the depletion transistor control region both transistors influence the total noise. Here the 1/f noise is dominated by the depletion transistor. The series resistance is only of importance in the linear regio

Modeling random telegraph noise under switched bias conditions using cyclostationary RTS noise

In this paper, we present measurements and simulation of random telegraph signal (RTS) noise in n-channel MOSFETs under periodic large signal gate-source excitation (switched bias conditions). This is particularly relevant to analog CMOS circuit design where large signal swings occur and where LF noise is often a limiting factor in the performance of the circuit. Measurements show that, compared to steady-state bias conditions, RTS noise can decrease but also increase when the device is subjected to switched bias conditions. We show that the simple model of a stationary noise generating process whose output is modulated by the bias voltage is not sufficient to explain the switched bias measurement results. Rather, we propose a model based on cyclostationary RTS noise generation. Using our model, we can correctly model a variety of different types of LF noise behavior that different MOSFETs exhibit under switched bias conditions. We show that the measurement results can be explained using realistic values for the bias dependency of /spl tau//sub c/ and /spl tau//sub e/

Thermal equilibrium noise with 1/f spectrum from frequency independent dielectric losses in barrium strontium titanate

We investigated the dielectric losses of doped and undoped BaSrTiO3 (BST) from thermal noise measurements. The results are compared to impedance measurements. The value for the frequency independent loss angle is about tg d = 2×10-2 in the range 10

Analytical expressions for the conductance noise measured with four circular contacts placed in a square array

In the ideal case, noise measurements with four contacts minimize the contribution of the contact interface. There is a need to characterize conductance noise and noise correction factors for the different geometries provided with four contacts, as already is the case for resistivity measurements with van der Pauw structures. Here, we calculate the noise correction factors for two geometries with a pair of sensors and a pair of current driver electrodes placed in a square array. The first geometry investigated is a very large film compared to the distance L between four circular electrodes, which are placed in a square array far away from the borders of the film. The second is a square-shaped conductive film with side length L and provided with four quarter-circle corner contacts with radius l. The effect of the conductance noise in the film can be observed between current free sensors in a four-point measurement or between current carrying drivers in a two-point measurement. Our analytical expressions are based on approximations to solve the integrals (J·)2dA and |J|4dA for the voltage noise measured across a pair of sensors, SVQ, and across the drivers, SVD, respectively. The first and second integrands represent the squared dot product of the current density and adjoint current density and the modulus of the current density to the fourth power, respectively. The current density J in the samples is due to the current I passing through the driver contacts. The calculated expressions are applicable to samples with thickness tl0.1L. Hence, the disturbances in the neighborhood of the sensors on J and of the drivers on are ignored. Noise correction factors for two- and four-point measurements are calculated for sensors on an equipotential (transversal noise) with the driver contacts on the diagonal of a square and for sensors next to each other on one side of the square with the drivers next to each other on the other side of the square (longitudinal noise). In all cases the noise between the sensors is smaller and less sensitive to the contact size 2l/L than the noise between the drivers. The ratio SVQ/SVD becomes smaller with smaller contact radius l. Smaller sensors give a better suppression of interface noise at the contacts. But overly low 2l/L values result in overly high resistance between the sensors and too strong a contribution of thermal noise at the sensors. Therefore, equations are derived to calculate the current level needed to observe 1/f conductance fluctuations on top of the thermal noise. The results from the calculated analytical expressions show good agreement with experimental results obtained from the noise in carbon sheet resistance and numerical results. Transversal noise measurements on a square sample with corner contacts are recommended to characterize the 1/f noise of the layer. This is due to the increased current densities in the sample compared to the open structure, which result in easier detection of the 1/f on top of the thermal noise. ©2007 American Institute of Physic