The charge carrier capture–emission process – the main source of the low-frequency noise in homogeneous semiconductors

Abstract

The possibility of determination of the number of localized capture centers of defects (relaxators) that cause low-frequency noise in a particular frequency range has been investigated. Here it is shown that a minimum number of relaxators is needed to generate 1/f type low-frequency noise only when relaxation times are arbitrarily distributed one-by-one in every two-octave range. The expression for estimation of the low-frequency noise level of the sample under test is presented. The presented expression for 1/f noise explains not only the noise level dependence both on the frequency and number of defects in the sample but also the observed noise intensity dependence on the mobility of free charge carriers. It is shown that the main source that causes low-frequency noise in homogeneous semiconductors is the charge carrier capture-emission process.

InGaAs Diodes for Terahertz Sensing—Effect of Molecular Beam Epitaxy Growth Conditions

“…Typical low-frequency noise spectra of the investigated InGaAs bow-tie detector B204 at different forward bias at room temperature (298 K) are presented in Figure 7 (the noise spectra for other samples as well as backward current direction at room temperature are almost the same as for the forward current direction, and therefore are not given here). The 1/ f -type-voltage noise spectra show that the observed fluctuations are caused by the superposition of the charge carrier capture and emission processes in defects in the InGaAs layer and its interfaces [ 29 , 30 , 31 ].…”

Charge carrier mobility fluctuations due to the capture–emission process

“…Considering that the relative changes of both the free charge carrier density and mobility due to free charge carrier capture are completely correlated (Eq. (10)), the relative conductivity fluctuations can be presented as In papers [15,16], it has been shown that the expression of the spectral density of the resistance fluctuations caused by free charge carrier number N fluctuations due to the capture-emission process in independent localized capture states (relaxators) can be presented as ,…”

“…When the number of relaxators of a particular type with particular relaxation times is many times greater than the average number of relaxators with other relaxation times, one can observe the Lorentzian type spectrum over 1/f noise. The presented analysis shows that the charge carrier capture and emission process is the main source for generating 1/f noise and random telegraph signal (RTS) noise [15,16]. It was also shown that for some homogeneous semiconductors in a particular doping range the charge carrier density n gives such proportionality for the mobility μ: μ 2 ~ 1/n.…”

“…An analysis of physical mechanisms of the lowfrequency noise in homogeneous materials, presented in papers [15,16], shows that a vision on proportionality of the resistance fluctuation spectral density to the inverse number of the free charge carriers can be explained only as an inverse proportionality to the sample volume because the ratio be-tween the numbers of defects and free electrons in the investigated homogeneous samples hardly depends on the volume at all. The minimum number of active defects (relaxators) with relaxation times distributed in a wide time range needed for generating the 1/f noise law in a given frequency range has also been estimated, and this requirement is fulfilled when the relaxation times are arbitrarily distributed one-by-one in every two-octave range.…”

Low-frequency noise of near UV LEDs

“…As known, in semiconductor devices 1/f α -type fluctuations originate as a result of the superposition of Lorentzian-type spectra due to different capture and emission processes of charge carriers in defects with a very wide distribution of relaxation times [20,21]. The series resistance-limited current tends to dominate at about 100 mA for the AII LEDs and for the samples of groups B-D at 5-50 mA.…”