Noise In Diodes Research Articles

Analytical model of high-frequency noise spectrum in Schottky-barrier diodes

We propose an analytical model for the high-frequency noise of Schottky-barrier diodes (SBD). The high-frequency spectrum is shown to be governed by collective motions of carriers in the neutral region of the SBD caused by the self-consistent electric field. The model is validated by comparison with Monte Carlo simulations of GaAs SBDs operating from barrier-limited to flatband conditions.

Giant suppression of avalanche noise in GaN double-drift impact diodes

By Monte Carlo simulations, we investigate the current voltage characteristic and the associated current noise in GaN double-drift impact avalanche diodes. For values of the current multiplication factor greater than ten we find a giant suppression of avalanche noise down to three order of magnitude with respect to the standard excess noise factor. The negative feedback between fluctuations in space charge and in number of generated electron–hole pairs is proven to be the responsible of such a giant suppression.

Low-frequency noise and charge transport in light-emitting diodes with quantum dots

In this experimental study, we have compared low-frequency (LF) noise and transport characteristics of light-emitting diodes (LEDs) with InAs quantum dots embedded in the In0.15Ga0.85As matrix with diodes of similar epitaxial structure without dots. Quantum dot (QD) and quantum well (QW) diodes have the p-i-n structure. At cryogenic temperatures, the LEDs with quantum dots exhibit pure excess tunneling transport mechanism, which originates from the energy levels introduced by quantum dots into the band gap of the intrinsic region. In the LEDs without quantum dots, an excess tunneling current was observed for small current densities. At a higher bias, another transport mechanism dominates, whose features can be explained by the Fowler-Nordheim (FN) tunneling. The low-frequency noise associated with the excess tunneling current is of 1∕f type and its power spectral density depends on the bias as S1∝I. In the diodes without dots, the relation S1∝I2 is valid at the bias, where the current transport mechanism is of Fowler-Nordheim type. In both cases, the considered noise spectral densities do not depend on temperature. We derived the explanation of the observed noise features for the QD and the QW devices on the basis of formulas for fundamental and nonfundamental noise sources, respectively. We measured the LF noise of the light emitted by idodes at room temperature and it appeared that it is a shot noise, which is not correlated with electrical noise.

Coherent approach to transport and noise in double-barrier resonant diodes

We implement a quantum approach which includes long range Coulomb interaction and investigate current voltage characteristics and shot noise in double-barrier resonant diodes. The theory applies to the region of low applied voltages up to the region of the current peak and considers the wide temperature range from zero to room temperature. The shape of the current voltage characteristic is well reproduced and we confirm that even in the presence of Coulomb interaction the shot noise can be suppressed with a Fano factor well below the value of 0.5. This feature can be an indication of coherent tunneling since the standard sequential tunneling predicts in general a Fano factor equal to or greater than the value 0.5. This giant suppression is a consequence of Pauli principle as well as long range Coulomb interaction. The theory generalizes previous findings and is compared with experiments.

Compact Conversion and Cyclostationary Noise Modeling of pn–Junction Diodes in Low-Injection—Part II: Discussion

Starting from the compact conversion and cyclostationary p-n diode noise model presented in the companion paper , we present an extensive validation based on comparisons with physics-based numerical simulations. Furthermore, we discuss the validity of two widely exploited system-oriented cyclostationary noise modeling approaches, based on the modulation of small-signal stationary noise spectra. We demonstrate that care must be exerted in the choice of the modulation scheme, unless the intrinsic diode noise is purely white, in which case a simple modulated shot noise approach can provide, with proper inclusion of parasitics, satisfactorily accurate results.

Characteristics of a semiconductor laser coupled with a fiber bragg grating with arbitrary amount of feedback

Stationary characteristics (such as laser frequency at threshold, light-intensity curve, etc.) and relative intensity noise of laser diodes coupled with an external Bragg reflector are studied for arbitrary amount of optical feedback. We put the stress on the interplay between external and internal cavities when the feedback strength is increased. For strong feedback, new stationary solutions that do not exist in the case of conventional feedback appear, while the ellipse, which usually contains the modes and so-called antimodes, collapse in the plane frequency-gain. Finally, analytical expressions are compared with numerical results obtained through a new approach that uses Green functions.

The Different Physical Origins of 1/f Noise and Superimposed RTS Noise in Light-Emitting Quantum Dot Diodes

Low frequency noise characteristics of light-emitting diodes with InAs quantum dots in GaInAs layer are investigated. Two noise components were found in experimental noise records: RTS, caused by burst noise, and 1/f Gaussian noise. Extraction of burst noise component from Gaussian noise background was performed using standard signal detection theory and advanced signal-processing techniques. It was found that Hooge's empirical relation applied to diodes by Kleinpenning is applicable to the electric 1/f noise in quantum dot diodes as well. Two different spectra decomposition techniques are used to obtain burst noise spectra. Bias dependences of burst and 1/f noise are compared. It is concluded that the RTS noise and 1/f noise have different physical origins in light-emitting diodes with quantum dots.

Extraction of an avalanche diode noise model for its application as an on‐wafer noise source

AbstractThis paper presents a method to characterize the excess noise ratio (ENR) of an unmatched avalanche noise diode for application as an on‐wafer noise source. It is based on the determination of a broadband device noise circuit‐model from its measured reflection coefficient and noise powers. Measured ENR is used to calibrated a noise receiver up to 40 GHz. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 89–92, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10979

Extended robust semiconductor laser modeling for analog optical link simulations

An enhanced semiconductor laser model incorporating gain nonlinearities, gain saturation, index nonlinearities, leakage current, thermal effects, and noise effects is presented. Symbolically defined devices based on the proposed models are implemented in the Hewlett-Packard Advanced Design System computer-aided design tool. The laser model enables the simulation of the transient and steady-state dynamic characteristics of laser diodes such as carrier, photon concentration, optical power, and phase. Using the proposed model, important laser characteristics such as relaxation-oscillation peak frequency and modulation bandwidth are evaluated under different conditions and compared to published measurement results. Analog optical transmission performance limitations such as laser diode nonlinearity and noise are determined in both the time and frequency domains.

Low frequency noise of GaAs Schottky diodes with embedded InAs quantum layer and self-assembled quantum dots

The electrical properties of InAs quantum layer (QL) and self-assembled quantum-dots (QDs), embedded in GaAs, are investigated by low-frequency noise measurements using Au/n-GaAs Schottky diodes as test devices. The measurements are carried out in the forward conduction regime with forward current IF as a parameter. Current–voltage and capacitance–voltage measurements indicate that GaAs and GaAs/InAs-QL Schottky diodes are nearly ideal, even though defects are present in the space–charge region of GaAs/InAs-QD Schottky diodes. In GaAs and GaAs/InAs-QL Schottky diodes, the power spectral density of the current fluctuations, S1, shows 1/f behavior and is proportional to IF2, which is explained by modulation of the barrier height due to trapping and detrapping phenomena. In GaAs/InAs-QD Schottky diodes, S1 shows 1/fγ (with γ≈0.6) behavior and is proportional to IF2 in the low current region and proportional to IF2.5 in the high current region. These noise data are explained by the generation of band tail states with exponential energy distribution in the GaAs layers due to QD formation.

Design and performance of a high‐stability water vapor radiometer

The design of two new high‐stability microwave water vapor radiometers is presented along with a performance evaluation. The radiometers operate next to a spacecraft tracking station at NASA's Goldstone facility in California, where they will be used to calibrate tropospheric path delay fluctuations during an upcoming gravity‐wave search experiment (GWE) involving the Cassini spacecraft. Observing frequencies of the radiometers are 22.2, 23.8, and 31.4 GHz, and the antenna beam width is 1°. The instruments are room temperature Dicke radiometers with additive noise injection for gain calibration. Design highlights include: (1) a practical temperature control system capable of stabilizing the entire receiver to a few millikelvin from day to night; (2) redundant noise diode injection circuits with 30 ppm RF power stability; and (3) a voice coil actuated waveguide vane attenuator which is used as a high‐performance Dicke switch. Performance of the radiometers is evaluated from intercomparisons of the two radiometers and from continuous tip curve calibrations spanning nearly 1 year. Structure function analysis of the intercomparison data indicates that the brightness temperature stability of these radiometers is better than 0.01 K on 1000–10,000 s timescales. Analysis of tip curve calibrations indicates RMS errors of ∼0.05 K on 30‐day timescales and 0.15 K on 1‐year timescales.

Leakage Current Behavior in Common I-Layer A-SI:H P-I-N Photodiode Arrays

AbstractHydrogenated amorphous silicon photodiode arrays form the basis of monolithic three-dimensional integrated circuit sensor technology. In these arrays, the intrinsic a-Si:H layer covers the entire area to maximize light collection. One technique by which the pixel diode is defined, is to pattern the bottom contact layer independently of the intrinsic layer. One of the most important characteristics of any diode array, however, is that the dark-state reverse bias leakage currents must be as low as possible to minimize diode noise. This study examines the leakage currents associated with the pixelated array. These structures are unique in that the edge of the diode is defined by the local electric field between diodes, rather than the physical surface of an a-Si:H film. The effect of the diode edge has been found to induce a field-dependent component to the reverse bias leakage current. For example, diodes with 5500Å i-layer, have a junction leakage of 14 to 20 pA/cm2, at 5.0 x 104 V/cm, while the pixel edge-dependent current component can be as high as 30 pA/cm2. In addition, it will be shown that the i-layer thickness and junction doping plays a key role in determining the behavior of the leakage currents.

Intensity noise and linewidth of laser diodes with integrated semiconductor optical amplifier

It is shown that the relative intensity noise and the linewidth of a laser diode can increase significantly if an optical amplifier is integrated with the laser diode. This increase is due to the amplified spontaneous emission from the optical amplifier.

Verification of magnetized electron series resonance from 1-D plasma diode noise current

A plasma diode appears resistive to an external observer at the magnetized electron series resonance (MESR). The authors derive the MESR resonant frequencies from an equivalent circuit model using linear cold plasma theory. The noise current from a decaying plasma is predicted to exhibit the MESR resonant frequencies and is verified by observing the spectra of the noise currents in 1d3v simulations. The spectra compare well with the theoretical values, which depend on the (central) plasma density and the sheath thickness. The latter is obtained from the (warm) plasma simulations.

Low frequency noise of reverse biased rectifier diodes in the avalanche breakdown regime

A detailed investigation of the low frequency noise in rectifier diodes in the breakdown regime showed that the noise is a nonmonotonic function of the reverse current. A dynamic “competition” between impact ionization and microplasma switching explains the nonmonotonic, repetitive, and correlated variations in the breakdown slope (change in voltage per unit change in current—dV/dI), the noise level, and the noise waveform. These variations are due to the bistable microplasma fluctuation. The theories for avalanche charge multiplication and microplasma fluctuation should be combined with the microplasma switching theory to develop a physical model for the avalanche breakdown.

Excess noise characteristics of Al/sub 0.8/Ga/sub 0.2/As avalanche photodiodes

The avalanche noise characteristics of Al/sub 0.8/Ga/sub 0.2/As have been measured in a range of p-i-n and n-i-p diodes with i-region widths /spl omega/ varying from 1.02 to 0.02 μm. While thick bulk diodes exhibit low excess noise from electron initiated multiplication, owing to the large /spl alpha///spl beta/ ratio (1/k), the excess noise of diodes with /spl omega/ < 0.31 μm were found to be greatly reduced by the effects of dead space. The thinnest diodes exhibit very low excess noise, corresponding to k = 0.08, up to a multiplication value of 90. In contrast to most III-V materials, it was found that both thick and thin Al/sub 0.8/Ga/sub 0.2/As multiplication layers can give very low excess noise and that electrons must initiate multiplication to minimize excess noise, even in thin structures.

The low frequency noise in reverse biased rectifier diodes

The low frequency noise in rectifier diodes in the breakdown regime is investigated as a function of the reverse current. A dynamic "competition" between impact ionization and microplasma switching explains the nonmonotonic, repetitive and correlated variations in the breakdown dynamic resistance (dV/dI) slope, the noise level, and the noise waveform.

Electron transport and shot noise in double-barrier resonant diodes: The role of Pauli and Coulomb correlations

We present a theoretical study of electron transport and shot noise in double barrier resonant diodes within the sequential tunneling model. We investigate the role played by Pauli principle and Coulomb interaction on the current voltage $(I\ensuremath{-}V)$ characteristics and the Fano factor by varying carrier concentration and lattice temperature. At $4.2\mathrm{K}$ we obtain the bistable $I\ensuremath{-}V$ characteristics of Z type. In the region of low and intermediate voltages for a sufficiently low electron concentration in the contacts the Fano factor exhibits two successive suppressed regimes associated with Pauli blockade and Coulomb correlation, respectively. By further increasing the voltage shot noise enhancement is found to be a precursor indicator that the device is approaching an instability regime in analogy with the case of phase transitions. In the bistable region hysteresis effects on different transport and parameters are analyzed. At $77\mathrm{K}$ and increasing temperatures for a carrier concentration of $5\ifmmode\times\else\texttimes\fi{}{10}^{16}{\mathrm{cm}}^{\ensuremath{-}3}$ the diode exhibits the usual negative differential conductance (NDC) characteristic. For voltages below NDC only Coulomb correlation remains effective, leading to a suppressed Fano factor intermediate between $0.5--1.$ For voltages just above NDC a moderate enhancement of the Fano factor up to values around 8 is evidenced. Theoretical findings provide a detailed physical interpretation of experimental results available in the literature and predict features to be confirmed by further experiments.

Intensity noise in quantum-dot laser diodes

We present intensity noise studies of a self-organized InAs/GaAs quantum-dot laser. The noise power measured for the full emission spectrum was found to be smaller than that for separate longitudinal mode groups. This noise cancellation indicates that the intensity fluctuations of the mode groups were anticorrelated, with typical values of the normalized correlation coefficient of around −0.50. This surprisingly high value is not consistent with the model of the quantum-dot laser as an inhomogeneous ensemble of independent microlasers.

Generation of physical random digits using diode noise and its statistical properties

AbstractThis study deals with a method of random number generation using hardware as a source of random signals. The random signals are produced by shot noise generated by a Zener diode and are converted into sequences of high‐quality random numbers. The proposed method is an improvement compared to conventional hardware‐based methods due to the fact that randomness of generated numbers is not affected by irregular performance characteristics of the hardware. This new method was verified by generating approximately 1.2 × 109 decimal random integers and by testing such characteristics of the generated random number sequences as their uniformity and independence by statistical methods. Results of the verification confirmed that characteristics of the random sequences obtained by this method were most satisfactory. © 2001 Scripta Technica, Electron Comm Jpn Pt 3, 84(11): 29–36, 2001