Low-frequency Noise Characteristics Research Articles

Modeling and characterization of low frequency noise in self-aligned top-gate coplanar IGZO thin-film transistors

Abstract A modified low-frequency noise (LFN) model was proposed to accurately estimate the quality of the gate dielectric in self-aligned top-gate (SA TG) coplanar structure indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs). The proposed LFN model was derived by modifying the conventional carrier number with correlated mobility fluctuation model considering the peculiar characteristics of SA TG coplanar IGZO TFTs such as the channel length reduction due to the diffusion of hydrogen atoms or oxygen vacancies from the source/drain to the channel, as well as the relatively large source/drain parasitic resistance. The proposed model was validated by demonstrating that the measured LFN values were in good agreement with the predicted values from the proposed model for all SA TG coplanar IGZO TFTs with SiO2 gate dielectrics deposited under different plasma-enhanced chemical vapor deposition (PECVD) power densities. The near-interface gate dielectric trap densities extracted from each TFT using the proposed LFN model revealed a clear increase as the PECVD power increased, which is considered a major cause of poor positive-bias-temperature-stress stability of the SA TG coplanar IGZO TFT with SiO2 gate dielectric deposited under high PECVD power conditions.

Low Frequency Electronic Noise Characterization of Au-W/β-Ga2O3 Schottky Diodes

Ultra-wide bandgap (UWBG) semiconductors have attracted tremendous amount of interest for applications in high-power electronics and solar-blind UV photodetectors. In particular, β-Ga2O3 has attracted significant research attention in recent years due to its promising electrical and optical characteristics including a large bandgap, high breakdown electrical field, and large Baliga’s figure of merit compared to well-established wide-bandgap technologies such as GaN and SiC [1].Low frequency electronic noise, which is present in all electronic devices, can be used as a diagnostic tool for semiconductor material and device characterization. By studying the low frequency noise in semiconductor materials and devices, the physics associated with the noise properties of bulk and interface defects and traps can be investigated [2]. Measurement of low frequency noise is also crucial for evaluating material quality and device reliability.In this work, we investigate the forward-bias diode parameters and low-frequency electronic noise in Au-W/β-Ga2O3 Schottky barrier diodes. The Schottky contact is formed by depositing 20 nm of Tungsten (W) using dc sputtering followed by 340 nm of Gold (Au) using e-beam evaporation, and subsequent annealing [3].We first measure the I-V characteristics and extract important diode parameters, such as the Schottky barrier height, ideality factor, and series resistance from room temperature forward-bias current-voltage characteristics. The extracted Schottky barrier height for these devices is in the range 0.7-0.8 eV and the ideality factor is approximately 1.2.We next measure the low-frequency electronic noise in Au-W/β-Ga2O3 Schottky diodes at different forward bias voltages at room temperature. We find that the current noise spectral density exhibits 1/f-type behavior for all forward bias voltages at low frequency with an exponent ranging from 0.75 to 1.15, indicating that the low frequency noise of these devices is dominated by excess (flicker) noise. No Lorentzian-shaped generation-recombination (G-R) noise is observed. At low frequencies, the shot noise contribution is found to be negligible for the values of the current in our devices, and the total noise is 1/f-limited.We also investigate the dependence of the current noise spectral density on forward bias current, revealing different relationships in different current regimes. At low currents, the noise spectral density is found to scale approximately as the square of current, whereas at high currents, the noise spectral density begins to saturate. Such noise behavior can be attributed to different noise sources dominating in different current regimes. Furthermore, using the noise figure of merit adapted for ultra-wide bandgap semiconductor devices [4], we find that the Au-W/β-Ga2O3 devices have lower noise levels compared to other emerging UWBG materials and similar noise levels as well-established technologies such as GaN.These results provide important insights into the electronic noise properties of Au-W/β-Ga2O3 Schottky diodes and show that low frequency noise characterization is an important diagnostic tool for assessing the quality and reliability of gallium oxide based wide-bandgap materials and device technologies.

Interface trap-induced radiofrequency and low-frequency noise analysis under temperature variation of a heterostacked source L-gate tunnel field effect transistor

This work offers a comprehensive analysis of the adverse impact of interface trap charge (ITC) under the influence of temperature variation on a heterostacked (HS) source L-gate tunnel field effect transistor (TFET) having a SiGe pocket. An investigation of both static and radiofrequency (RF) characteristics has been carried out. It appears that ITCs situated at the Si–oxide interface fluctuate the flat-band voltage to alter the various analog/RF parameter characteristics. Uniform ITCs are seen to be less susceptible to degradation in device characteristics. Low-frequency noise (LFN) analysis has also been carried out considering the impact of different trap distributions (uniform and Gaussian) and densities, which are compared. The temperature dependence of LFN has been studied under the influence of different distributed ITCs, and this has rarely been explored. Moreover, a comparative analysis has been made of the device behavior and LFN characteristics of HS L-gate TFET structures with and without a SiGe pocket. Structures with SiGe pockets were found not to be susceptible to noise effects.

Toward Ideal Low-Frequency Noise in Monolayer CVD MoS2 FETs: Influence of van der Waals Junctions and Sulfur Vacancy Management.

The pursuit of sub-1-nm field-effect transistor (FET) channels within 3D semiconducting crystals faces challenges due to diminished gate electrostatics and increased charge carrier scattering. 2D semiconductors, exemplified by transition metal dichalcogenides, provide a promising alternative. However, the non-idealities, such as excess low-frequency noise (LFN) in 2D FETs, present substantial hurdles to their realization and commercialization. In this study, ideal LFN characteristics in monolayer MoS2 FETs are attained by engineering the metal-2D semiconductor contact and the subgap density of states (DOS). By probing non-ideal contact resistance effects using CuS and Au electrodes, it is uncovered that excess contact noise in the high drain current (ID) region can be substantially reduced by forming a van der Waals junction with CuS electrodes. Furthermore, thermal annealing effectively mitigates sulfur vacancy-induced subgap density of states (DOS), diminishing excess noise in the low ID region. Through meticulous optimization of metal-2D semiconductor contacts and subgap DOS, alignment of 1/f noise with the pure carrier number fluctuation model is achieved, ultimately achieving the sought-after ideal LFN behavior in monolayer MoS2 FETs. This study underscores the necessity of refining excess noise, heralding improved performance and reliability of 2D electronic devices.

Study of the Extremely Low-Frequency Noise Characteristics of a Micro-Thrust Measurement Platform.

The critical structural parameters are optimized and studied using the numerical simulation method to improve the resolution and stability of the Micro-Thrust Measurement Platform (MTMP). Under two different ground random vibration environments, the parameters, such as pivot thickness, pendulum rod length, and pivot structure, are focused on analyzing the influence of the system's resolution and stability. The results show that when the thickness of the pivot is 0.04 mm or 0.2 mm, and the pendulum rod length is 2 m, the effect of ground random vibration on the MTMP is minimized. At 0.1 mHz, it can reach 0.0057 μN/Hz. In the series double-pivot structure, an appropriate increase in the distance between the sheets can further optimize the above conclusions. The results and analysis within this study can provide support for the engineering design of the MTMP.

Discrete Distribution Model of Ship Noise Source in Shipping Channel

Ship noise plays an important role in low-frequency ocean ambient noise. With the increasingly busy sea traffic, the randomness of the spatiotemporal distribution characteristics of ship noise is also increasing. However, most ships sail in a relatively fixed range in different sea areas. Most of the previous studies assumed that the ship noise sources in shipping channel satisfy a uniformly distribution, actually all kinds of large ships are not uniformly distributed in the shipping channel, and there are also many small boats distributed on the channel that contribute significantly to low-frequency ocean ambient noise. The channel within a certain sea area will be divided into different regions, and ship information (AIS) in different regions will be analyzed statistically in this paper. It is assumed that the ship noise sources in different channel regions are discrete point noise sources that obey a certain spatiotemporal statistical distribution, combined with the noise source level models of different types of ships to form a discrete source model of ship noise in shipping channel. Using the ray propagation theory considering the horizontal refraction of sound energy, the vertical distribution of the ship noise level in this sea area is calculated, and compared with the vertical noise level distribution of ship noise source uniform distribution model, the variation range of noise level vertical distribution of two models is close calculated noise level (such as maximum and minimum values) is consistent with the measured data. The discrete source model of ship noise established in this paper may provide a technical support for predicting low-frequency ambient noise characteristics near the channel.

Characterization of DC performance and low-frequency noise of an array of nMOS Forksheets from 300 K to 4 K

The DC and low-frequency noise performance of an array of 800 parallel Forksheet MOSFETs were investigated by performing measurements over a wide temperature range from 300 K to 4 K. The array structure allowed to measure a representative average performance of the devices and provided a large effective area for 1/f noise analysis. Results showed an improvement in the saturation drain current when going from room temperature to cryogenic temperatures, with the subthreshold swing saturating around 100 K and the threshold voltage shifting by approximately 150 mV, following similar trends observed in Silicon cryogenic electronics. Additionally, the study confirms that the noise at cryogenic temperatures does not follow the commonly assumed linear scaling with temperature. This deviation from the linear scaling has been associated with the presence of tail states at the interface in bulk and silicon-on-insulator (SOI) devices. These results suggest that the excess 1/f noise in this advanced device architecture is not related to the device architecture but rather to the microscopic material properties of semiconductor/dielectric interfaces.

Low-frequency noise characterization of positive bias stress effect on the spatial distribution of trap in β-Ga2O3 FinFET

The reliability of a β-Ga2O3 thin-film field-effect transistor is investigated under positive-bias stress (PBS). The transistor has a tri-gate structure with a gate dielectric of Al2O3. By characterizing low-frequency noise (LFN), the spatial distribution of trap in the gate dielectric was quantitatively extracted. The measured power spectral density (PSD) followed a 1/f-shape due to trapping and de-trapping of the channel carriers to and from the gate dielectric. Notably, the vertical distribution of the traps perpendicular to the interface of β-Ga2O3 and Al2O3 was mapped

Low Frequency Noise Behavior in Resistive Memory Devices with Hf/HfO2 Stack

Resistive-random-access-memory (RRAM) devices are considered to be one of the most potential candidates of next generation emerging memory technologies due to their excellent device properties, such as high density, low power, low voltage, and high speed. RRAM features simple metal–insulator–metal (MIM) structures and is fully compatible with traditional CMOS fabrication processes. Low-frequency noise (LFN) measurement is a technique to characterize electrically the trap-assisted conduction processes in dielectrics. In this work, we report the LFN characteristics of Hf/HfO2-based bipolar RRAM and investigate the current conduction mechanism and internal physics.

Ionizing radiation influence on 28-nm MOS transistor's low-frequency noise characteristics

In this paper, we explore the transitions of low-frequency noise characteristics in high-k metal-gate bulk CMOS transistors induced by Total Ionizing Dose (TID). Due to the strong bias dependence of the noise characteristics, differentiating between noise shifts caused by the effective biasing change and the contribution of the newly generated traps becomes extremely challenging. In order to better understand the effects of irradiation, transistor noise had to be characterized at several biasing points, both in linear and saturation regions, before and after exposure to 1 Grad (SiO2) of TID. Correlation between shifts in time and frequency domain is presented in this work, along with possible explanations for each variation that occurs. We present examples of irradiation-generated Random Telegraph Noise (RTN) defects as well as various TID effects on noise Power Spectral Density (PSD) curves with pre-existing RTN sources.

Effect of heavy ion radiation on low frequency noise characteristics of AlGaN/GaN high electron mobility transistors

AlGaN/GaN high election mobility transistor (HEMT) has important application prospects in satellite communication, radar, nuclear reactors and other extreme environments, owing to its excellent electrical performance and strong radiation resistance. Heavy ion radiation mainly causes single-event effect and displacement damage effect in AlGaN/GaN HEMT device. In this work, the displacement damage defects introduced by heavy ion radiation are analyzed in detail. With the increase of heavy ion radiation influence, more defects are introduced by displacement damage. These defects reduce the two-dimensional electron gas (2DEG) concentration through carrier capture and removal effect, and reduce the carrier mobility through scattering mechanism, resulting in gradual degradation of the electrical characteristics of the device. In this work, AlGaN/GaN high electron mobility transistors are irradiated by <sup>181</sup>Ta<sup>32+</sup> ions with fluences of 1×10<sup>8</sup> ions/cm<sup>2</sup>, 1×10<sup>9</sup> ions/cm<sup>2</sup> and 1×10<sup>10</sup> ions/cm<sup>2</sup>. The electrical characteristics, EMMI and low-frequency noise characteristics of the device before and after heavy ion radiation are measured. The results show that heavy ion radiation can lead to the degradation of electrical parameters. When the heavy ion radiation dose reaches 1×10<sup>10</sup> ions/cm<sup>2</sup>, the electrical characteristics of the device deteriorate seriously, the threshold voltage shifts forward by 25%, and the drain saturation current deteriorates obviously. The defect locations introduced by irradiation are analyzed by EMMI test, and it is found that the number of “hot spots” increases significantly after the having been irradiated by heavy ions with a fluence of 1×10<sup>10</sup> ions/cm<sup>2</sup>, indicating that the radiation leads to the increase of defect density and serious damage to the device. Through the noise test, it is found that with the increase of the radiation fluence, the current noise power spectral density gradually increases. When the fluence reaches 1×10<sup>10</sup> ions/cm<sup>2</sup>, the defect density increases to 3.19×10<sup>18</sup> cm<sup>–3</sup>·eV<sup>–1</sup>, and the Hooge parameter increases after having been irradiated by heavy ions. We believe that the radiation leads to the defect density and parasitic series resistance of AlGaN/GaN HEMT device to increases, resulting in larger Hooge parameters. Through analyzing the variation of the normalized power spectral density of the drain current noise with bias voltage, it is found that the defects caused by heavy ion radiation will cause the parasitic series resistance to increase.

Low-Frequency Noise Characteristics of Recessed Channel Ferroelectric Field-Effect Transistors

Low-Frequency Noise Characteristics of Recessed Channel Ferroelectric Field-Effect Transistors

Improvement of low-frequency noise behavior with chloridic precursor materials at ALD process

This article reports an improvement in the low-frequency noise characteristics in hafnium oxide-based (HfO2) field-effect transistors by different precursor materials at ALD process. The Hafniumoxide on the devices were fabricated once with organic precursor materials and once with chloridic precursor materials. The investigation shows an improvement in the noise behavior when using chloridic precursor materials. Regarding the main noise source, which are divided into fluctuation of the number of carriers (ΔN) and fluctuation of the effective transistor mobility (Δμ), the results show that the devices fabricated with organic precursor materials show typical behavior of ΔN noise, where the devices fabricated with chloridic precursor materials show typical behavior of Δμ noise.

Determining the Electron Scattering from Interfacial Coulomb Scatterers in Two-Dimensional Transistors.

Two-dimensional (2D) transistors are promising for potential applications in next-generation semiconductor chips. Owing to the atomically thin thickness of 2D materials, the carrier scattering from interfacial Coulomb scatterers greatly suppresses the carrier mobility and hampers transistor performance. However, a feasible method to quantitatively determine relevant Coulomb scattering parameters from interfacial long-range scatterers is largely lacking. Here, we demonstrate a method to determine the Coulomb scattering strength and the density of Coulomb scattering centers in InSe transistors by comprehensively analyzing the low-frequency noise and transport characteristics. Moreover, the relative contributions from long-range and short-range scattering in the InSe transistors can be distinguished. This method is employed to make InSe transistors consisting of various interfaces a model system, revealing the profound effects of different scattering sources on transport characteristics and low-frequency noise. Quantitatively accessing the scattering parameters of 2D transistors provides valuable insight into engineering the interfaces of a wide spectrum of ultrathin-body transistors for high-performance electronics.

Unveiled Influence of Sub‐gap Density of States on Low‐Frequency Noise in Si‐Doped ZnSnO TFTs: Does Correlated Mobility Fluctuation Model Suffice?

AbstractThe presence of low‐frequency noise (LFN) in amorphous oxide semiconductor (AOS) thin‐film transistors (TFTs) is of utmost concern, prompting extensive investigations into the analysis of LFN. However, prior research endeavors have tended to overlook the significance of the sub‐gap density of states (DOS) in the LFN analysis, resulting in an incomplete comprehension. To bridge this knowledge gap, the influence of sub‐gap DOS is demonstrated on LFN in Si‐doped ZnSnO (SZTO) thin‐film transistors (TFTs) under various conditions. The SZTO TFTs is intentionally subjected to positive bias stress and hot carrier stress in order to control the sub‐gap DOS and investigate how this change affects the LFN characteristics. It is revealed that the non‐uniform energetic distribution of sub‐gap DOS induces bias‐dependent excess noise in the SZTO TFTs. Additionally, self‐recovery behavior after the HCS is observed, accompanied by a commensurate reduction in 1/f noise. These empirical observations provide evidence that the conventional correlated mobility fluctuation model used to explain LFN in AOS TFTs is insufficient and underscores the critical importance of considering subgap DOS when analyzing LFN of AOS TFTs.

Pulsed Low-Frequency Noise Characterization on Al/ZnO/Al ReRAM to Investigate the Role of Deep-Level Oxygen Vacancy State in HRS Leakage

Pulsed Low-Frequency Noise Characterization on Al/ZnO/Al ReRAM to Investigate the Role of Deep-Level Oxygen Vacancy State in HRS Leakage

Effect of Trap Behavior on the Reliability Instability of Metamorphic Buffer in InAlAs/InGaAs MHEMT on GaAs.

Our investigation focused on assessing the influence of the metamorphic buffer in metamorphic high-electron-mobility transistors (MHEMT) that were grown on GaAs substrates. While an MHEMT exhibited elevated off-state current levels, its direct current (DC) and radio frequency (RF) traits were found to be comparable to those of InP-based lattice-matched high-electron-mobility transistors (LM-HEMTs). However, the Pulsed I-V measurement results confirmed the presence of the fast transient charging effect, leading to a more substantial degradation in drain current observed in MHEMT. In addition, through the low-frequency noise characteristics, it was confirmed that the dominant trapping location was located in the bulk site. The slope of the 1/f noise measurement indicated that the primary trapping site was in proximity to the bulk traps. The carrier-number-fluctuation (CNF) model was employed to extract the bulk trap density (Nt). For the LM-HEMTs, the value was at 3.27 × 1016 eV-1·cm-3, while for the MHEMT, it was 3.56 × 1017 eV-1·cm-3.

(Invited) In-Depth DC and Low Frequency Noise Characterization of Nanosheet FETs at Room and Cryogenic Temperatures

In this work, an in-depth static and low frequency noise characterization of nanosheet FETs, consisting of two vertically stacked silicon channels per device, is performed. A comparison of the performances from n- versus p-channel FETs operated at 300 K and 78 K, in terms of static and low frequency noise parameters variability, is also discussed.The studied devices were fabricated at imec. The geometrical dimensions of the devices are the following: each fin presents a width of 15 nm and each nanosheet thickness is around 11 nm. The effective channel width is calculated as Weff = 2·N·(2·Wfin + 2·Hfin), where N is the number of fins in parallel in the layout and per device. The equivalent oxide thickness is around 0.9 nm. Two structures having different vertical distance between the stacked nanosheets: 7.5 nm (wafer#1) and 4.7 nm (wafer#2) are investigated. Overview results focus on devices having a fixed gate length (LG) of 100 nm and 22 fins in parallel (N = 22) [1,2] but preliminary results on devices having LG = 70 nm and N = 2 are also presented. More information about the device fabrication and the experimental setup used for the various types of measurements covered in this work can be found in [3,4].Typical drain current and transconductance transfer characteristics for n- and p-channel devices from wafer#1 operated at 78 K are illustrated in Figure 1. The main static parameter extraction of the devices operated in ohmic regime is made comparing two methodologies which are not affected by the access resistance impact, as Y-function [5,6] and the McLarty equations [7] methodologies. Good agreement between the extracted parameters using these two methods is obtained in particular when the simple criteria proposed in [1] are employed. Indeed, criteria in [1] allow to properly choose the applied gate voltage interval for which the parameter extraction using Y-function should be made when the impact of the surface roughness collisions in the mobility expression cannot be neglected.An example of input-referred noise spectra, at different applied gate voltages, for n-channel devices from wafer#1 operated at 78 K is shown in Figure 2. White noise, flicker noise and depending on the polarization one or more Lorentzian noise contributions may be observed on the total input-referred noise spectra for all investigated devices. The noise parameters are estimated using methodologies presented in [4,8]. It is demonstrated that the 1/f noise mechanism may be explained by the carrier number fluctuations correlated to the mobility fluctuations mechanism [9] from weak to moderate inversion operation, while in strong inversion operation the 1/f noise behavior is dominated by the access resistances noise [10] contribution. It is shown that the access resistance parameter is the key parameter in order to not underestimate the Coulomb scattering coefficient value.Overall, we have found that the wafer#1 devices present good electrical properties in terms of mobility, threshold voltage, access resistance and even from a flicker noise level point of view, for both n- and p-channel nanosheet FETs, while devices from wafer#2 with a smaller separation between the nanosheets suffer more from mobility variability and high access resistances due to a non-optimized process flow.References :[1] Cretu et al., accepted in IEEE Trans. Electron Dev.[2] Cretu et al., Solid-State Electron, 2022, 194, pp. 102-108, 108209, DOI: 10.1016/j.sse.2022.108360.[3] Veloso et al., SSDM Tech. Dig., 2019, pp. 559-560, DOI: 10.7567/SSDM.2019.N-1-03.[4] Boudier et al., Solid-State Electron, 2017, 128, pp. 102-108, DOI: 10.1016/j.sse.2016.10.012.[5] Ghibaudo, Electronics Letters, vol.24, no. 9, p. 543, 1988, DOI: 10.1109/ICMTS.2000.844428.[6] Mourain et al., ICMTS 2000, pp. 181-186, 2000, DOI: 10.1109/ICMTS.2000.844428.[7] K. McLarty et al., Solid-State Electron., 1995, 38 (6), pp. 1175-1177, DOI: 10.1016/0038-1101(94)00248-E.[8] Boudier et al., Solid-State Electronics, vol. 168, DOI : 10.1016/j.sse.2019.[9] Ghibaudo et al., Phys. Status Solidi (a), 1991;124 (2), pp. 571-581, DOI : 10.1002/pssa.2211240225.D..107732.[10] F.N. Hooge, IEEE Trans. Electron Dev. 41, pp. 1926-1935, 1994. DOI: 10.1109/16.333808. Figure 1

Study on low-frequency noise characteristics of hydrogen-terminated diamond FETs

In this work, the low frequency noise (LFN) characteristics of Hydrogen-terminated diamond FETs are investigated. Both generation-recombination (GR) noise and flicker noise (1/f noise) are found to contribute to the LFN spectrum. The characteristic frequency of f01 = 0.1 Hz, f02 = 30 Hz, f03 = 300 Hz and corresponding effective trap density (Neff) of the GR centers are obtained. By changing the LFN measurement temperature, a trap activation energy level (Ea) of 0.12 eV is extracted from an Arrhenius plot. The dominant mechanism of the 1/f noise for the H-terminated diamond FETs follows the correlated mobility fluctuations (CMF) model. By fitting the experimental data to the CMF model, the trap density and scattering coefficient of the carriers are extracted to be 6.4×1020 eV−1 cm−3 and 4×105 V·s/C. At last, the trap density of the H-terminated diamond FETs is compared with other state-of-the-art GaN and Si based devices. A moderate trap density was obtained without any interface optimization, suggesting that H-terminated diamond FETs could be a promising future technology for power electronics.

Novel Y-function based strategy for parameter extraction in S/D asymmetric architecture devices and low frequency noise characterization in GAA Si VNW pMOSFETs

In this work, DC and low frequency noise measurements are performed in p-channel gate-all-around (GAA) silicon vertical nanowire (Si VNW) MOSFETs. The DC measurements highlight asymmetry in the drain current and transconductance transfer characteristic even in linear operation, at an applied drain voltage of −50 mV. A novel Y-function based strategy for parameter extraction in S/D asymmetric devices is proposed. This novel strategy allows the estimation of the value of each access resistance, from source and from drain sides, respectively, and allows overcoming the device asymmetry to provide an accurate extraction of the main DC parameters. The low-frequency noise studies on forward and reverse operation mode, demonstrate that the 1/f noise in both modes can be explained by the correlated carrier number (Δn) and mobility fluctuation (Δμ) mechanisms, with additional contribution of the access resistance noise in strong inversion.