Microplasma Noise Research Articles

Noise-based analysis of the reliability of silicon solar cells

With silicon solar cells as the research object, this paper takes their nondestructive character and analyzes their quality with noise-based technology. Through the stress aging of samples and the testing of various types of noise, including 1/f noise, microplasma noise, and G-R noise, in the cells in the laboratory, the noise characteristics are analyzed. The research results show that noise is correlated with defects in silicon solar cells. The different types of noise can be used to characterize different parts and types of defects in the cells according to the mechanism of generation of noise and the failure physics of photovoltaic devices, and thereby, the evaluation of the quality and analysis of the reliability of solar cells can be achieved.

FRACTAL PROPERTIES OF MICROPLASMA BREAKDOWN AND STRUCTURAL HETEROGENEITY OF SEMICONDUCTOR MATERIALS

This work presents experimental results on the study of current-voltage characteristics and oscillograms of microplasma pulses of the p-n-junction avalanche breakdown. Based on the latter, the pulse duration distributions are determined. As a result, it is shown that microplasma noise has fractal properties. The latter form the basis of avalanche breakdown types developed classification. The correlation between the fractal dimension of microplasma noise and structural inhomogeneities of functional semiconductor structures is revealed.

Simulation Approach to Modeling of the Avalanche Breakdown of a p–n Junction

The avalanche breakdown of a p–n junction is investigated experimentally in order to study the temporal distribution of microplasma pulses. It is revealed that the observed type of microplasma noise is not described by the existing model of processes occurring during the avalanche breakdown of a p–n junction. A computer model explaining the mechanisms of microplasma instability and taking into account the electric and temperature dependences of avalanche breakdown, which agrees with the experimental results, is developed using simulation modeling.

Имитационный подход к моделированию лавинного пробоя p-n-перехода

An experimental study of the avalanche breakdown of the p−n-junction was carried out in order to study the temporal distribution of microplasma pulses. It was revealed that the observed appearance microplasma noise is not described in the existing model processes that occur during avalanche breakdown of p−n-junction. Using simulation, a computer model was developed that clarifies the mechanisms of microplasma instability and takes into account the electrical and temperature dependences of avalanche breakdown, which is consistent with the results of experiments.

Micro-plasma noise of 30 krad gamma irradiation broken-down GaN-based LED * * Project supported by the Education Department Science and Technology Foundation of Jiangxi Province (No. GJJ160743) and the Doctoral Research Start-Up Foundation of Jinggangshan University (No. JZB15001).

A correlation model between micro plasma noise and gamma irradiation of GaN-based LED is built. The reverse bias I–V characteristics and micro-plasma noise were measured in it, before and after Gamma irradiation. It is found that even after 30 krad Gamma irradiation, the GaN-based LED has soft breakdown failure. The reverse soft breakdown region current local instability of this device before irradiation is analyzed by the micro-plasma noise method. The results were obtained that if the GaN-based LED contained micro-plasma defects, it will fail after low doses (30 krad) of gamma irradiation. The results clearly reflect the micro-plasma defects induced carriers fluctuation noise and the local instability of GaN-based LED reverse bias current.

Fractal properties of LED avalanche breakdown

The conventional model of the processes occurring in the course of a p–n-junction's partial avalanche breakdown has been analyzed in this paper. Microplasma noise spectra of industrially produced LEDs were compared with those predicted by the model. It was established that the data obtained experimentally on reverse-biased LEDs could not be described in terms of this model. The degree to which the fractal properties were pronounced was shown to be variable by changing the reverse voltage. The discovered fractal properties of microplasma noise can serve as the basis for further studies which are bound to explain the breakdown characteristics of real LEDs and to correct the conventional model of p–n-junction's avalanche breakdown.

Avalanche breakdown of p-n-junction in radiotechnics

The paper presents research results of fractal properties of microplasma noise at LED avalanche breakdown in the visible spectrum (λ= 660; 700 nm). The breakdown type of p-n-junctionwas determined as a result of measured current-voltage characteristics at room temperature, at the temperature of 100-105 °C and after cooling down to room temperature. It was shown that the breakdown of avalanche type is realized in the majority of LEDs. It was established that the partial avalanche breakdown mode may be realized in LEDs, when a small current flows in pulses through the device. By increasing the voltage, pulse amplitude increases, closely spaced pulses merge, and time intervals between them are reduced. To interpret experimental results we applied model of processes occurring in microplasma, and noise model of partial and advanced avalanche breakdown (by A.S. Tager). The study revealed previously non-described features of microplasma noise – the fractal nature of microplasma noise. The algorithm for fractal dimension calculating was implemented in MATLAB. The dependence of fractal dimension on the reverse voltage applied to the LEDs was found out. Obtained fractal signal can be applied in optical communication systems for noise free and confidential information transmission.

Microplasma Analysis and Noise Spectroscopy of c-Si Solar Cells

This paper deals with comparisons of noise spectroscopy and detection of microplasma noise sources in the three new type of solar cells G1, G3 and G5. When high electric field is applied to PN junction with some technological imperfections like dislocation in PN junction or crystal-grid defect causing non-homogeneity of parameters it produces in tiny areas of enhanced impact ionization called microplasma. It can leads onwards to deterioration in quality or to destruction of PN junction. Microplasma produced noise, which has random spectrum in frequency range. Microplasma noise is measurable even before the creation of light emissions. Due to the comparisons microplasma detection with noise characteristic can full analyzed solar cell.

Non-Destructive Characterization of Micro-Sized Defects in the Solar Cell Structure

This article discusses the issue of noise measurements application for the quality assessment of the solar cells themselves and production technology alike. The main focus of our research is the random n-level (in most case just two-level) impulse noise, usually referred to as microplasma noise. This noise was found to be in a direct consequence of local breakdowns in micro-sized regions and brings about a reduction of lifetime or a destruction of the pn junction. Non-destructive measurement methodology as presented here is suitable for testing of a large number of various semiconductor devices not only for solar cells. In this paper experimental measurement of noise signals in the frequency and time domain is presented. Furthermore the microplasma noise behaviour and defect geometry is discussed.

PN Junction Defects Detection in Solar Cells Using Noise Diagnostics

PN junction is one of the most important parts of solar cells. Its quality affects lifetime and efficiency of solar cells. Local defects which appear in PN junctions during the manufacture process are very important from this point of view. These are caused by localized areas with high donor or acceptor doping agents, impurities, dislocations or other mechanisms which effect in lower breakdown voltage of PN junction in reverse bias. Several base methods can be used for solar cells nondestructive diagnostics. Measuring methods of low-band noise current effective value with reverse bias junction were used in this paper. This method allows detection of local defects and volume degradation in PN junctions of solar cells and it can be used for detection of microplasma noise. This noise is an impulse noise and it is caused by local avalanche breakdowns in small area of the junction. It can be recognized by two or more level random square current pulses with constant height, random appearance time and random pulse length. Information about these effects can be used in noise diagnostics of structural defects of PN junctions and then it can be used for quality and lifetime estimation of samples with these parameters.

Theory of microplasma fluctuations and noise in silicon diode in avalanche breakdown

A theory that explains physically the mechanism of microplasma switching from nonconducting to conducting state (turn-on process) and from conducting to nonconducting state (turn-off process) is presented. This theory describes the microplasma phenomenon in avalanche breakdown, and it provides relations between the microplasma properties (size, current density, and turn-on-off mechanism), noise properties (amplitude and wave form), and semiconductor properties (impurity concentration, lifetime constants, and diffusion coefficients). By use of this theory, the current-fluctuation [McIntyre, IEEE Trans. Electron Devices ED-13, 164 (1966)] and probability-dependent [Haitz, J. Appl. Phys. 35, 1370 (1964)] theories can be combined, and a very attractive characterization tool for investigation of semiconductor junctions in breakdown is developed.

Microplasma Noise Stimulated by Microwave Electric Field

Si and GaAs avalanche diodes containing microplasmas are investigated.Microwave fleld applied to the diode in addition to reverse dc bias results inconsiderable spread of noise spectrum and in the increase of noise power. Themicroplasma noise spectra cover very high (30 to 300 MHz) and ultrahigh(300 to 1000 MHz) frequency bands, while the efiective noise temperature isabout 10

A stochastic model for microplasma noise

Taking a simple branching process as model of the carrier multiplication in reverse junctions, the turn-on probability of a microplasma is determined. Considering the variation of the voltage and current in the diode, the distribution of the off-state time interval is deduced. Finally, expressions for the amplitude distribution as well as the rate of discharges in units of time are developed in the case where the on-time is negligible.

Noise in luminescent GaAs 0·60P 0·40 diodes under non-uniform avalanche conditions—II

Current noise, light noise and the correlation between them (“current-light” noise) has been studied in luminescent GaAs 0·60P 0·40 diodes under non-uniform avalanche conditions. A simple model is proposed to describe the light noise and current-light noise in connection with the characteristic breakdown emission. The model is analogous to the model used to describe the light noise in cathodo-luminescent devices. The observation of the hard current-voltage characteristic, the tiny light spots and the characteristic microplasma noise indicate that the breakdown is caused by the avalanche effect. This has been confirmed by the measurement of the positive temperature coefficient of the breakdown voltage and the measurement of other avalanche breakdown quantities. Optical observations have shown that only a part of the cross sectional area of the junction is effective. The impedance measurements suggest that for most diodes the effective area increases linear with the current. For these diodes the multiplication factor remains approximately constant. The current noise spectra depend on the frequency in the low frequency range and show white noise in the high frequency range. The level of the white noise component exceeds the level calculated for uniform avalanche. For most diodes a small correlation has been measured in the light noise and a more distinct correlation between current noise and light noise.

Bistable noise in operational amplifiers

Bistable noise in operational amplifiers has been investigated. Equivalent circuits are used. It is shown that by changing the source resistance of an operational amplifier the locations of bistable noise sources can be determinated. Both burst noise and microplasma noise observed from an operational amplifier. The input transistors of an operational amplifier are the most important bistable noise sources. Burst noise due to elements other than the input transistors is shown to be important. Surface effects on burst noise have been discussed. Because of the surface effect, n-p-n transistors are expected to show more burst noise than p-n-p transistors. Microplasma noise in an operational amplifier is attributed to a local surface breakdown.

An investigation of microplasma noise in zener diodes with the SEM : C. J. Varker, Proc. IEEE Reliab. Phys. Symp., Las Vegas, U.S.A. 31 March–2 April (1971)

An investigation of microplasma noise in zener diodes with the SEM : C. J. Varker, Proc. IEEE Reliab. Phys. Symp., Las Vegas, U.S.A. 31 March–2 April (1971)

Bistable noise in p- n junctions

Two types of bistable noise, burst noise and microplasma noise, have been investigated with particular emphasis on that under reverse-bias operations. The physical models for them are reviewed and generalized, and the distinction between burst noise and microplasma noise is discussed. The experimental results indicate that the mechanism responsible for burst noise in a reverse-biased p- n junction is the same as that in a forward-biased p- n junction. It is also shown that the fluctuation amplitude of the effective potential barrier can be determined by the measurements of the amplitude of burst noise pulses as functions of temperature.

An investigation into the origin and nature of "Popcorn noise"

The phenomenon of popcorn noise is discussed and shown to exist in integrated wideband amplifiers when an input transistor of the amplifier exhibits a negative resistance region in the reverse-biased collector-base characteristic. A correlation is drawn between popcorn noise and microplasma noise.

Behaviour of silicon pn junctions at temperatures between 4-2 and 300° K†

This paper presents the results of an investigation into the effect of lattice temperature on the breakdown voltage of silicon pn junctions. Measurements have been made over the temperature range 4-2-300° K using devices with nominal breakdown voltages from 8 to 13 v. Results show that the influence of temperature can be separated into three distinct temperature intervals. For temperatures greater than 100° K the carrier mean free path is the controlling factor of the ionization rate and causes the voltage to decrease with decrease of temperature. At low temperatures (less than 30° k) the breakdown voltage increases with cooling because freeze out of carriers in the base allows a significant voltage to be developed across this region. Calculations involving this voltage drop enable the field required for ionization of impurities to be evaluated. In the intermediate temperature range traps are observed by studying microplasma noise and these appear to influence the ionization rate. In addition to the break...

Zener and avalanche breakdown in silicon alloyed p- n junctions—II : Effect of temperature on the reverse characteristics and criteria for distinguishing between the two breakdown mechanisms

The effect of temperature on the reverse current and breakdown voltage of silicon p- n junctions for a wide range of breakdown voltages has been investigated and the criteria for differentiating the Zener breakdown from avalanche breakdown have been presented. Narrow p- n junctions with soft characteristics have a temperature insensitive reverse current, contributed by internal field emission and show a negative temperature coefficient β of breakdown voltage which is determined up to large extent by the available phonon density present in tunnelling transitions. Wider junctions with V B > 13 V show a highly temperature sensitive current and a positive value of β, which is in good agreement with the avalanche multiplication theory. For values of V B from 3.5 to 13 V there is a transition region from Zener to avalanche type of breakdown in which the temperature dependence of the reverse characteristics is complex and cannot be accounted by a single mechanism. Apart from the temperature dependence of breakdown voltage such properties as generation of microplasma noise, dependence of breakdown voltage on impurity concentration, space-charge layer width and maximum field strength at breakdown have been found to show distinct differences between Zener and avalanche regions and give a further support to the conclusions reached from the temperature studies.