Low-frequency Generation-recombination Noise Research Articles

Discussion on the Figures of Merit of Identified Traps Located in the Si Film: Surface Versus Volume Trap Densities

In this work a discussion on the estimated volume trap densities (NT) compared to surface traps densities (Neff) related to identified traps in the Si fin of Si/SiGe superlattice I/O n-channel FinFETs using low frequency noise spectroscopy is made. The investigated devices present a fin width of 10 nm, a fin height of 10 nm and four fins in parallel, leading to an equivalent channel width of 120 nm. The equivalent oxide thickness (EOT) is 5.6 nm. More details on the device fabrication and experimental setup may be found in [1,2]. The noise spectra and the estimated surface traps densities are provided in [3]. In this work, focus is only on the identified T4 trap, for which using the linear dependence that should exist between A0i and t0i related to the same trap, without any other assumption, a surface trap density of 2.8∙1012cm-2 is obtained [3]. It should be noted that from the 1/f flat-band noise level an interface trap density value of about 1.9∙1018 eV-1cm-3 is obtained at 300 K.However, as the traps in the Si film are related to a volume phenomenon, two methodologies to estimate the volume trap densities are employed: one using the relationship between the surface trap density and volume trap densitiy [4], where B is a coefficient estimated to be 1/3 [4,5]; and a second one from the temperature (T) evolution at fixed frequency of the Lorentzian plateau level associated to the same trap (from equation 34 in [4]). Using the first method leads to a volume trap density of T4 of about 1.7∙1019 cm-3.The second method consists to use the maximum of the measured Svg_Lor(f 0,T) dependence with temperature. Indeed, the Svg_Lor(f 0,T) of Lorentzians associated to the same trap are proportional with ti(T)/{1 + [2pf 0ti(T)]2}. For a given frequency f 0, if 2pf 0ti(T) ≫ 1, SVg_Lor(f 0,T) ∝ ti(T)]-1, and SVg_Lor(f 0,T) increases with increasing temperature because ti decreases. If 2pf 0ti(T) ≪ 1, then SVg_Lor(f 0,T) ∝ ti(T) and SVg_Lor(f 0,T) decreases with increasing temperature, as explained in detail in [4]. The evolution of the Svg_Lor(f 0,T)∙f 0 in a temperature range where T4 traps are active is illustrated in Figure 1 and presents a bell-shaped behavior, as expected. Using this method, volume trap densities of about 1.25∙1018 cm-3 for f 0 = 10 kHz and of about 1.1∙1018 cm-3 for f 0 = 14 kHz are obtained. It may be observed that the estimated volume trap densities of the T4 defect are about one decade lower than when using the first method. This overestimation by the first method is related to the fact that the theoretical B coefficient was determined for conventional planar devices with one gate [4,5]. Moreover, it may be noticed that the second method is dependent on the fixed f 0 selected.The paper will present a discussion with more details, considering all identified traps in [1] and considering additional new low frequency noise spectroscopy results.References :[1] Hellings, H. Mertens, A. Subirats, E. Simoen, T. Schram, L.-A. Ragnarsson et al., “Si/SiGe superlattice I/O finFETs in a vertically-stacked Gate-All-Around horizontal Nanowire Technology”, in Tech. Dig. Symp. on VLSI Technology, The IEEE New York, 2018, p.p. 85-86, DOI: 10.1109/VLSIT.2018.8510654.[2] Boudier, B. Cretu, E. Simoen, R. Carin, A. Veloso, N. Collaert, and A. Thean, “Low frequency noise assessment in n- and p-channel sub-10 nm triple-gate FinFETs: Part I: Theory and methodology,” Solid State Electron., vol. 128, pp. 102-108, 2017, DOI: 10.1016/j.sse.2016.10.012.[3] Boudier, B. Cretu, E. Simoen, G. Hellings, T. Schram, H. Mertens and D. Linten, “Low frequency noise analysis on Si/SiGe superlattice I/O n-channel FinFETs”, In Proceedings of EUROSOI-ULIS’2019.[4] Lukyanchikova, “Noise and Fluctuations Control in Electronic Device”, edited by A. Balandin, American Scientific, Riverside, CA, 2002, pp. 201-233.[5] Yau and C-T. Sah, “Theory and experiments of low-frequency generation-recombination noise in MOS transistors”, IEEE Trans. Electron Dev., 1969, vol.16, pp. 170-177.Figure 1 : SVg_Lor(f 0,T)·f 0 versus temperature for the T4 trap identified in [3]; on the secondary Oy axis the characteristic frequency f 0i of the Lorentzians is displayed in function of temperature. Figure 1

Low-frequency generation-recombination noise behaviors of blue/violet-light-emitting diode

During the past two decades, GaN-based light-emitting diode has been used as a high-quality light-source. Low-frequency noise as a diagnostic tool for quality control and reliability estimation has been widely accepted and used for semiconductor devices. Understanding the origin of efficiency-droop effect is key to developing the ultimate solid-state light source. Various mechanisms that may cause this effect have been suggested, including carriers’ escape, loses due to dislocations, and the Auger effect. In this study, we investigate the low-frequency noise behaviors of GaN-based blue light-emitting diode with InGaN/GaN multiple quantum wells. The measured currents range from 0.1 mA to 180 mA. According to the characteristics of power spectral density of current noise and the generation-combination mechanism between electrons and holes in the active region of light-emitting diode (LED), we adopt the well-known model of low-frequency noise to fit the relationship between power spectral density of current and frequency, and find that there exists a transition between generation-combination and 1/<i>f</i> noise when the light-emitting diode begins to work. In other words, it can be derived that the low-frequency noise behaviors are dominated by generation-combination noise when the currents are between 0.1 mA and 27 mA; with the current gradually increasing, the origin source of low-frequency noise in blue/violet-light LED will transit to the 1/<i>f</i> noise. Through the analysis of the transport and recombination mechanism of the carriers, and combination with the model of low-frequency noise, we analyze the corner frequency of the generation-recombination noise. The results of this paper provide an effective tool and method to study the conversion of light-emitting diodes.

Two-dimensional semiconductor device simulation of trap-assisted generation-recombination noise under periodic large-signal conditions and its use for developing cyclostationary circuit simulation models

The simulation of generation-recombination (GR) noise under periodic large-signal conditions in a partial differential equation-based silicon device simulator is presented. Using the impedance-field method with cyclostationary noise sources, it is possible to simulate the self- and cross-spectral densities between sidebands of a periodic large-signal stimulus. Such information is needed to develop noise correlation matrices for use with a circuit simulator. Examples are provided which demonstrate known results for shot noise in bipolar junction transistors. Additional results demonstrate the upconversion of low-frequency GR noise for microscopically cyclostationary noise sources and provide evidence for applying the modulated stationary noise model for low-frequency noise when there is a nearly quadratic current dependence.

Low-frequency generation–recombination noise in fully overlapped lightly doped drain MOSFETs

A model for generation–recombination (g–r) noise in FOLD MOSFETs is presented incorporating the field dependent mobility and the bias dependent series resistance. The g–r noise is due to the emission and capture of carriers in the space charge region in the bulk-channel junction. It is observed that noise power increases with increasing drain voltage and decreases with decreasing gate voltage. The results so obtained are compared with the experimental data.

Asymmetry in the dark current low frequency noise characteristics of B–B and B–C quantum well infrared photodetectors from 10 to 80 K

We present experimental results demonstrating the significant effect that the type of intersubband transition has on the dark current noise of quantum well infrared photodetectors containing 32 Si-doped GaAs quantum wells separated by ∼350 Å thick AlxGa1−xAs barriers. The experimentally observed asymmetry in the noise characteristics is similar but larger than the asymmetry between dark currents under forward and reverse bias voltages. We are able to control the ratio between the components of the dark current by biasing with constant current and varying the temperature over an extended range well below the intended operational point. Our results indicate a clear relationship between the excessive low-frequency generation-recombination noise and the thermally assisted tunneling component of the dark current. We have also found indications that the excessive 1/f like noise component can be related to the tunneling process in direct well-to-well tunneling and to thermally assisted tunneling dark current mechanisms.

Erratum [for "Burst and low-frequency generation-recombination noise in double-heterojunction bipolar transistors"

The following error appeared in the article by X.N. Zhang et al., "Burst and low-frequency generation-recombination noise in double-heterojunction bipolar transistors," IEEE Electron Device Lett., vol. EDL-5, no. 7, pp. 277-279, July 1984. In Figs. 2, 3, and 4 S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_B</sub> must be multiplied by a factor of 100. S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_B</sub> is therefore much larger than the shot nolse of the base current. There is now indication of two generation-recombination noise bumps in Figs. 2 and 3. All other conclusions remain intact.

Supression of drain conductance transients, drain current oscillations, and low-frequency generation—Recombination noise in GaAs FET's using buried channels

The drain conductance transients of buried-channel MESFET's fabricated on GaAs are compared with conductance transients of regular MESFET's. The buried-channel MESFET's are shown to be essentially free of drain transients in comparison to the regularly fabricated MESFET's. In addition, the buried-channel FET's are shown to be free of oscillations in the drain current, which have been found in FET's manufactured by common techniques.

Burst and low-frequency generation-recombination noise in double-heterojunction bipolar transistors

The low-frequency noise in a double-heterojunction bipolar transistor (DHBT) consisted of burst noise and generation-recombination g-r noise. The current dependence of the base burst noise with floating collector was of the form I B 3and the current dependence of the collector g-r noise with HF short circuited base was as I C 3/2. The centers involved in the noise generation had an activation energy of about 0.40 eV, with an indication of a second center of lower energy in the collector noise.

Geometrical dependences of the low-frequency generation-recombination noise in mos transistors

A comparison between theory and experiments for the dependences of generation-recombination noise on the gate-oxide thickness and the channel length of MOS transistors is presented. The results show good agreements between theory and experiments.

Theory and experiments of low-frequency generation-recombination noise in MOS transistors

A theoretical model for the generation-recombination (g-r) noise in MOS transistors is presented. This model takes into account the charge induced on all electrodes by the charge fluctuation of the impurity center in the depletion region. The model gives a finite equivalent gate noise resistance at saturation. Gold-doped and no-gold control devices were fabricated to verify the theory experimentally. The drain-voltage dependence of the g-r noise, which is shown to be distinctly different from the 1/f noise and thermal noise, is used to check the theory. Good agreement between theory and experiment is obtained.