A. V. Yakimov

A simple test of the Gaussian character of noise

Abstract The test consists in the measurement of the noise intensity at the output of a bandpass filter, and the estimation of the accuracy of the measurement. The confidence interval for the estimate is calculated under the assumption that the noise is stationary and Gaussian. This assumption is called “zero-hypothesis”. If a considerable part of the experimental data is outside the confidence interval, then the zero-hypothesis does not hold. The effect of noise being non-Gaussian is investigated analytically. Experimental data of 1/ f noise in GaAs epitaxial films are presented and discussed.

Erratum 2 : 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 Hooges 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.

COMPLEXES OF SPATIALLY MULTISTABLE DEFECTS AS THE SOURCE OF 1/f NOISE IN GaAs DEVICES

In order to determine the origin of 1/f noise in devices made on the basis of GaAs the structure and spatial multistability mechanism of complexes of defects originated by donor–acceptor pairs are researched. Examples of complexes, which potentially exist in n-GaAs:Si, are such pairs as SiAsSiGa, VGaSiGa, VGaVAs, VAsSiAs and VGaISi. For instance, VGaSiGa complex contains a gallium vacancy (VGa) and an atom of silicon (SiGa), which substitutes the nearest atom of gallium in the crystal lattice. The mechanism of spatial multistability of the entire complex of defects is linked with the influence of the Jahn–Teller effect on the complex or one of its elements. The ability of VGaSiGa complex to be one of the sources of 1/f noise is analyzed. It is assumed that 1/f noise may be generated by defects influenced by the Jahn–Teller effect.

MODIFICATION OF VAN DER ZIEL RELATION FOR SPECTRUM OF NOISE IN p-n JUNCTION

Spectrum SiD of the white current noise iD(t) in p–n junction with the ideality factor η of the current–voltage characteristic, which is greater than one, is investigated here. It is shown, that the Van der Ziel relation, SiD = 2q(ID + 2Is), intended for η = 1, is inapplicable if η > 1; here q is the elementary charge, ID is the current through the junction, and Is is the saturation current. As the first step, the simplest case is considered, η = 2. That is the main recombination of injected electrons and holes takes place in the middle of the junction depleted region. Such junction may be modeled by two identical junctions with η = 1, which are connected in series. The current noise iD(t) is determined by noise sources of both junctions. Obtained result is generalized by the use of the Gupta theorem for the thermal noise spectrum in nonlinear resistive systems. The current noise spectrum is found, SiD = (2q/η) · (ID + 2Is). This result is the modification of the Van der Ziel relation extended to η ≥ 1. Experimental proof of the modified relation is made by analysis of the white noise spectrum in Schottky diode with δ-doping (having η = 2.2) in the vicinity of thermodynamical equilibrium.

PHYSICAL ORIGINS OF 1/f NOISE IN Si δ-DOPED SCHOTTKY DIODES

A model of Schottky diode with δ-doping is suggested. The aim is the determination of technological areas of the diode, which are responsible for the 1/f noise. Series resistance of base and contacts, and the possible leakage are taken into account. Equivalent parameters of the diode are defined from the analysis of the current–voltage characteristic. The model of fluctuations in the charge of non-compensated donors in δ-layer of Schottky junction (ΔNs – model) and model of 1/f noise in leakage current are suggested for an explanation of experimental data. Our study show that, in the investigated diodes, in a million atomic impurities, there are about 1–10 special impurity atoms with stochastically modulated ionization energy.

1/f Noise in Ti–Au/n-Type GaAs Schottky Barrier Diodes

We have studied the forward current–voltage (I–V) characteristics of Ti–Au/n-type GaAs Schottky barrier diodes. However, we found some anomalies in I–V characteristics. Hence, we have considered a model that incorporates thermionic emission, thermionic-field emission and leakage components. Leakage component is linear and visible at rather small currents. The anomalies observed in the diode parameters were effectively construed in terms of the contribution of these multiple charge transport mechanisms across the interface of the diodes. It is shown that thermionic-field emission and leakage are the sources of low-frequency (1/f) noise in such type of diodes. Various Schottky diode parameters were also extracted from the I–V characteristics and current dependence of spectrum of 1/f voltage noise.

Modification of A. Van der Ziel relation for natural noise in diodes with non‐ideality factor of I–V characteristic η>1

The spectrum of natural noise in junction of the diode with non‐ideality factor of the I–V characteristic greater than one, η>1, is investigated. It is shown, that the model by A. Van der Ziel is inapplicable for η>1 in the region of small currents (except the “ideal” case η = 1). At small currents the spectrum of noise is described by the Nyquist relation. To solve this problem we accept that the I–V characteristic is described by a few “ideal” junctions connected in serial; in case of η = n = 1, 2, 3,… these may be n identical junctions. The total current noise includes noise sources of all junctions. The presented result is the modification of A. Van der Ziel relation for η⩾1.

1/F Noise In Si Delta‐Doped Schottky Diodes

The model of Schottky diode with δ‐doping is suggested. This one is aimed for the determination of technological areas of the diode, which are responsible for the 1/f noise. Series resistance Rb of base and contacts, and the possible leakage Ileak are taken into account. Parameters of the diode are defined from the analysis of the current‐voltage characteristic. For an explanation of experimental data the model of fluctuations in the charge of non‐compensated donors in δ‐layer of Schottky junction (ΔNs‐model) is suggested. The analysis of the 1/f noise spectrum allows assuming that, in investigated diodes, on 106 atoms of main impurity there are 1–10 atoms of extraneous impurity the ionization energy of which may stochastically be modulated.

1/F Noise In Leakage Current Of Nanoscale Light Emitting Structures

The 1/f voltage noise in prototypes of light‐emitting diodes (LEDs) with InAs quantum dots (QDs), LEDs with InAs QDs and In0.2Ga0.8As quantum wells (QWs) and In0.2Ga0.8As/GaAs/InGaP lasers with QWs was investigated. Optical intensity noise in spontaneous emission regime in QW lasers has been investigated as well. The leakage current is the main source of voltage 1/f noise. Noise in electrical parameters of QWs and QDs was not detected.

Differences in dependence of 1/f and RTS noise on current in quantum-dot light-emitting 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 Hooges empirical relation applied to diodes by Kleinpenning is applicable to the electric 1/f noise of 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.