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Random two-level or multiple-level current impulses may occur in electronic devices containing reverse biased p-n junctions in a certain operating mode. These impulses are usually rectangular, featuring constant amplitude, random pulse width and pulse origin time points. This phenomenon is generally ascribed to local avalanche breakdowns originating in p-n junction defect regions called microplasma regions. Based on experiment results, a two-state model of stochastic generation-recombination process has been elaborated for the two-level impulse noise allowing to derive some statistical characteristics of this process. It can be shown that the distribution of the probability density w(τ₀) of the impulse separation τ₀ and the probability density w(τ₁) of the impulse width τ₁ have exponential courses. The power spectral density of the noise current is of a G-R process type and depends on the particular microplasma properties. From the viewpoint of noise diagnostics, the most important features are the spectral density S_u and noise current I_N versus reverse current I_R plots, because each local extreme of these plots corresponds to an active microplasma region. Thus obtained results may be used for p-n junction non-destructive diagnostics and quality assessment.

A physically-based transient model for low frequency noise of both microplasma and impact ionization in PN diodes is discussed and implemented in the SPICE simulator. The simulation indicates that the model correctly describes the non-monotonic behavior of both the DC and the noise characteristics of diode at the onset of avalanche breakdown. The model is based on a new microplasma switching theory, and the results of simulation confirm the findings of this theory. The microplasma switching threshold is the condition of equality of free- to space charge concentration in the depletion layer. The microplasma turn-on is initialized by the charge generation due to few recombination centers in the microplasma region at high avalanche multiplication due to impact ionization. The microplasma on-current is approximately twice the threshold current and the on-current sustains until the low, but larger than 1, avalanche multiplication compensates for the carrier diffusion from microplasma region into the depletion layer. When the multiplication becomes lower than the diffusion, the microplasma switches off.

A physically-based transient model for low frequency noise of both microplasma and impact ionization in PN diodes is discussed and implemented in the SPICE simulator. The simulation indicates that the model correctly describes the non-monotonic behavior of both the DC and the noise characteristics of diode at the onset of avalanche breakdown. The model is based on a new microplasma switching theory, and the results of simulation confirm the findings of this theory. The microplasma switching threshold is the condition of equality of free- to space charge concentration in the depletion layer. The microplasma turn-on is initialized by the charge generation due to few recombination centers in the microplasma region at high avalanche multiplication due to impact ionization. The microplasma on-current is approximately twice the threshold current and the on-current sustains until the low, but larger than 1, avalanche multiplication compensates for the carrier diffusion from microplasma region into the depletion layer. When the multiplication becomes lower than the diffusion, the microplasma switches off.