Correlated Mobility Fluctuations 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.

(Invited) Generic Compact Model for Variability and Low-Frequency Noise in Organic Thin-Film Transistors

In organic thin-film transistors (OTFT), low-frequency noise (LFN) is dominated mainly by grain-boundary traps and mobility fluctuation [1]. Accurate LFN modeling of OTFTs has been successfully demonstrated in [2] by adopting the theory of carrier-number and correlated mobility fluctuations (ΔN noise) [3,4,5] and the empirical Hooge approach accounting for mobility fluctuation due to percolative effects (Δµ noise) [6,7]. Furthermore, OTFTs are sensitive to process variability. Charges being trapped in the channel region cause a local variation of the accumulated charge density, having impact on the threshold voltage of the device [8,9] and reducing the effective carrier mobility in the channel by Coulomb scattering. As a result, the drain-current variability is also correlated to carrier-number and correlated mobility fluctuations and therefore allows for a similar modeling approach as for ΔN noise [9].Based on the results published in [2,9], we present a generic physics-based modeling approach for drain-current fluctuations by carrier-number and correlated mobility fluctuations, which leads to similar expressions for drain-current variability and ΔN noise in OTFTs. The model is based on the charge-based compact model for OTFTs presented in [10]. Starting from the local fluctuation of the current in the channel, closed-form model equations have been derived for the fluctuation of the total device current. The final expressions (1) for drain-current variability and (2) for ΔN noise show the same bias dependent part B*(qch) given by equation (5). An individual bias-independent prefactor C* is obtained. In case of drain-current variability this factor in equation (3) depends on the density Nt of trapped charges. For ΔN noise, in (4), NT is the density of traps per energy available for capture and release of charge carriers.Measurements performed on fabricated OTFTs in staggered (C10-DNTT) or coplanar (Dph-DNTT) architectures (Fig. 1) show that the drain-current variability in the subthreshold regime is dominated by carrier-number fluctuations, whereas for above threshold operation the mobility-fluctuation effect by correlated Coulomb scattering comes to the fore (Fig. 2) [9]. In case of LFN, measurements on staggered DNTT OTFTs have shown that ΔN noise alone is not sufficient to describe the noise spectra in the deep subthreshold regime of operation (Fig. 3) [2]. Here, LFN due to mobility fluctuation (Δµ noise) must be included with equations (6-8), which results in an additional and different bias dependent expression with a prefactor including the empirical Hooge parameter. The total LFN is given by (9).In conclusion, following a generic modeling approach, the combined equations for carrier-number and correlated mobility fluctuations and for percolative mobility fluctuation allow consideration drain-current variability and LFN noise in a charge-based compact model of OTFTs in all regions of operation and is in good agreement with results from measurements. Acknowledgements: This project was funded by the German Federal Ministry of Education and Research ("SOMOFLEX", No. 13FH015IX6), German Research Foundation (DFG) under Grant KL 1042/9-2 (SPP FFlexCom), the Spanish Ministry of Science (PRX21/00726), and the EU EIC-PATHFINDER (BAYFLEX, no 101099555). We acknowledge AdMOS GmbH, Germany, for support, and Max Planck Institute for Solid State Research Stuttgart, Germany, for fabrication of devices.

Low-frequency noise in InSnZnO thin film transistors with high-quality SiO2 gate oxide stacks

Low-frequency noise (LFN) in InSnZnO (ITZO) thin-film-transistors (TFT) with high-quality SiO2 gate oxide (GO) stacks is studied. This stack is fabricated by the plasma enhanced chemical vapor deposition (PECVD) and comprises two single layers. One layer is deposited by a SiH4 source (SiH4–SiO2), and the other uses a tetraethyl-orthosilicate precursor (TEOS-SiO2). The drain current noise power spectral densities follow the typical 1/f rule, and the main origin of LFN changes with the variation of drain current intensities. At low drain current intensities, LFN is affected by grain boundaries in the channel. As the drain current intensities increase, LFN originates from the carrier number fluctuations in devices with single TEOS-SiO2 GOs and from the carrier number with correlated mobility fluctuations in devices with SiO2 stacks GOs. At extremely high drain current intensities, the contact noise acts as a significant source of LFN in devices with SiO2 GO stacks. According to the carrier number with correlated mobility fluctuation (ΔN−Δμ) model, the devices with optimal stacks GOs exhibit a relatively low trap density near the ITZO/SiO2 interface. Additionally, these devices have a lower border trap density in GOs compared to those with single compositions. It demonstrates that high-quality SiO2 stacks reduce traps near the SiO2/ITZO interface, leading to enhanced devices performance. This work provides a precise and efficient method to evaluate the quality of GOs in metal oxide TFTs.

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.

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.

Universality of trap-induced mobility fluctuations between 1/f noise and random telegraph noise in nanoscale FD-SOI MOSFETs

Low frequency noise (LFN) and random telegraph noise (RTN) are investigated statistically on nanoscale MOSFETs of 28 nm fully depleted silicon-on-insulator technology. The analysis reveals that the mean noise level is well described by the carrier number fluctuations with a correlated mobility fluctuations model. As for the RTN, it is shown that the mean amplitude of signals is driven by correlated mobility fluctuations in strong inversion. The comparison between the extracted parameters of the LFN and RTN analysis demonstrates that the remote Coulomb scattering impact due to the trapped and detrapped charges remains the same on average for this technology, whether it is the average noise spectrum of all devices or the average amplitude of the detected RTN signals.

Interface traps, correlated mobility fluctuations, and low-frequency noise in metal–oxide–semiconductor transistors

Interface traps generally are not considered to be likely sources of low-frequency (LF) noise and/or random telegraph noise (RTN) in metal–oxide–semiconductor (MOS) devices because the longer carrier exchange times of border traps are more consistent with experimental observations. In contrast, correlated mobility fluctuations due to remote Coulomb scattering from charged border traps cannot explain the unexpectedly large LF noise and/or RTN observed in some MOS devices. In this Letter it is proposed that equilibrium fluctuations in interface-trap concentrations caused by hydrogen-induced activation and passivation reactions can lead to enhanced LF noise and RTN. This mechanism adds to other noise sources, including border traps, random dopants, and bulk-Si defect clusters.

Refined DC and Low-Frequency Noise Characterization at Room and Cryogenic Temperatures of Vertically Stacked Silicon Nanosheet FETs

In this work, two types of gate-all-around (GAA) vertically stacked silicon nanosheet (NS) FETs are investigated, the main difference being the vertical distance between the stacked NSs. Principal electrical parameters are estimated at room and liquid nitrogen temperatures using a refined <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Y}$ </tex-math></inline-formula> -function methodology, the main advantage being that no extra iterative steps are necessary. The results are confirmed using other derivative dc parameter estimation methodologies. Low-frequency noise measurements evidence variability of the flat-band voltage noise and correlation between the noise level and the low field mobility. The dominant flicker noise mechanism is related to the correlated mobility and carrier number fluctuation mechanism with access resistance noise contribution in very strong inversion. The impact of the access resistance on the estimation of the Coulomb scattering coefficient is evidenced.

New insights into low frequency noise (LFN) sources analysis in GaN/Si MIS-HEMTs

We present a thorough investigation of the low frequency (LF) noise in the access and channel regions in GaN MIS-HEMT devices. The 1/f noise behaviour is caused by trapping/de-trapping processes which are well described by carrier number fluctuations (CNF) and correlated mobility fluctuation (CMF) models. To address the issue of LF noise in the access and channel regions of GaN MIS-HEMT devices, we have tested respectively “non-gated” and “gated” devices with different designs. The border trap density extracted in optimized devices at AlGaN/GaN and Al2O3/GaN interfaces is better than previously reported GaN data and close to silicon CMOS results. This enabled us to show a controlled LF noise level and even improved one, emphasizing the progress in the manufacturing process of advanced GaN technologies. Due to the gate channel shape of GaN MIS-HEMT devices with recessed gate, a new CNF/CMF noise model including access resistance noise source is also proposed. It enables a reliable parameter extraction in each channel region, authorizing device noise modeling over a large set of GaN MIS-HEMT process and design.

Low-Frequency Noise Modeling of Amorphous Indium–Zinc-Oxide Thin-Film Transistors

An improved model for the low-frequency noise (LFN) of amorphous indium–zinc-oxide thin-film transistors (a-IZO TFTs) is developed in this article. For a-IZO TFTs, the LFN is not only attributed to the oxide traps in the gate insulator but also affected by the discrete trap centers in the active-layer film. This makes the device has excess noise in the subthreshold region, which is obviously different from monocrystalline silicon (c-Si) MOSFETs. Therefore, we put forward an accurate and physically meaningful model to characterize this excess noise. For the subthreshold region, the charge of tail states in the channel is considered to describe the excess subthreshold noise, and the channel density of states (DOS) is extracted, confirming the effectiveness of the model. For the above-threshold region, the classic carrier number with correlated mobility fluctuation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta N$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \mu $ </tex-math></inline-formula> ) mechanism has been investigated to explain the noise behavior. Furthermore, the proposed unified model is validated, and it has been successfully applied to a-IZO TFTs with different tail-state densities.

DC and low-frequency noise characteristics of GaN-based HEMTs under cryogenic temperatures

In this work, the device characteristics of GaN-based high-electron-mobility transistors (HEMTs) were systematically investigated by the direct current (DC) and low-frequency noise (LFN) measurements within the temperature ranging from 300 K to 4.2 K. The temperature-dependent behavior of the on- and off-state electrical properties was statistically analyzed, highlighting an overall improved device performance under cryogenic temperatures. In addition, the LFN of the device exhibited an evident behavior of 1/f noise from 10 Hz to 10 kHz in the measured temperature range and can be well described by the carrier number fluctuations with correlated mobility fluctuations (CNF/CMF) model down to 4.2 K. Based on this model, we further extracted and discussed the defect-related behavior in the devices under low-temperature environments. These experimental results provide insights into the device characteristics of GaN-based HEMTs under cryogenic environments, motivating further studies into the GaN-based cryo-devices and systems.

Analysis of Low Frequency Noise in Schottky Junction Trigate Silicon Nanowire FET on Bonded SOI Substrate

In this work, low frequency noise (LFN) in Schottky junction trigate silicon nanowire (SiNW) field-effect transistors (FETs) (SJGFETs) fabricated on bonded silicon on insulator (SOI) substrate is systematically analyzed. The LFN exhibited a typical 1/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}$ </tex-math></inline-formula> spectrum and can be well described by the carrier number fluctuation (CNF) with correlated mobility fluctuation (CMF) model. It was found that CNF is the dominant component of the LFN, while CMF associated with the Coulomb scattering near the buried oxide (BOX)/SiNW channel interface plays an insignificant role. Applying a substrate bias can further modulate the LFN of the SJGFETs, and the effect is ascribed to the nonuniform energy distribution of the BOX/SiNW channel interface traps. Confining current path in the channel bulk away from the interface brought limited gain in terms of LFN performance. Finally, our experimental results suggested a possible transition of CMF mechanism from Coulomb scattering to surface roughness scattering when the current path is pushed away from the BOX/SiNW channel interface to the channel bulk.

Ultraviolet-Assisted Low-Thermal-Budget-Driven α-InGaZnO Thin Films for High-Performance Transistors and Logic Circuits.

Developing a low-temperature fabrication strategy of an amorphous InGaZnO (α-IGZO) channel layer is a prerequisite for high-performance oxide-based thin film transistor (TFT) flexible device applications. Herein, an ultraviolet-assisted oxygen ambient rapid thermal annealing method (UV-ORTA), which combines ultraviolet irradiation with rapid annealing treatment in an oxygen atmosphere, was proposed to realize the achievement of high-performance α-IGZO TFTs at low temperature. Experimental results have confirmed that UV-ORTA treatment has the ability to suppress defects and obtain high-quality films similar to high-temperature-annealing-treated samples. α-IGZO/HfAlO TFTs with high-performance and low-voltage operating have been achieved at a low temperature of 180 °C for 200 s, including a high μsat of 23.12 cm2 V-1 S-1, large Ion/off of 1.1 × 108, small subthreshold swing of 0.08 V/decade, and reliable stability under bias stress, respectively. As a demonstration of complex logic applications, a low-voltage resistor-loaded unipolar inverter based on an α-IGZO/HfAlO TFT has been built, demonstrating full swing characteristics and a high gain of 13.8. Low-frequency noise (LFN) characteristics of α-IGZO/HfAlO TFTs have been presented and concluded that the noise source tended to a carrier number fluctuation (ΔN) model from a carrier number and correlated mobility fluctuation (ΔN-Δμ) model. As a result, it can be inferred that the low-temperature UV-ORTA technique to improve α-IGZO thin film quality provides a facile and designable process for the integration of α-IGZO TFTs into a flexible electronic system.

Optimization of channel structure and bias condition for signal-to-noise ratio improvement in Si-based FET-type gas sensor with horizontal floating-gate

Sensing performances of the Si-based field-effect transistor (FET)-type gas sensor are not only affected by sensing material characteristics but also by electrical properties of a transducer. Therefore, the optimization of transducer properties, including subthreshold swing, transconductance, and low-frequency noise (LFN) characteristics, is necessary for improving the sensing performances. In this paper, NO2 gas sensing properties, LFN characteristics, and signal-to-noise ratio (SNR) of the FET-type gas sensor having different channel structures (surface and buried channel FETs) are investigated. An n-type indium-gallium-zinc oxide (IGZO) thin-film is used as a sensing layer. The LFN characteristics of both sensors are explained using a carrier number fluctuation model with correlated mobility fluctuation. The flat-band voltage fluctuation (SVfb) value of the buried channel (4.54×10−10 V2/Hz) is smaller than that of the surface channel (2.73×10−9 V2/Hz). Thus, the SNR of the sensor with a buried channel shows ~10 times larger SNR than that with a surface channel. Also, the optimal bias conditions for both sensors are suggested. The sensor with buried channel FET has a limit of detection (LOD) of 44.2 ppt to NO2 gas.

Effects of High-Pressure Annealing on the Low-Frequency Noise Characteristics in Ferroelectric FET

In this work, the low-frequency noise (LFN) characteristics of hafnium-zirconium oxide (HZO) ferroelectric field-effect transistors (FeFETs) with and without high-pressure forming gas annealing (HPA) treatment are investigated. The origin of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1/ {f}$ </tex-math></inline-formula> noise in the FeFET without HPA is changed from carrier number fluctuation to Hooge’s mobility fluctuation after wake-up due to the remote phonon scattering from the polarized HZO. Also, Hooge’s parameter is increased by the program/erase (P/E) cycling-induced stress. On the contrary, only the correlated mobility fluctuation is increased after the wake-up in the FeFET with HPA. Furthermore, the LFN of the FeFET with HPA shows robustness to P/E cycling-induced stress after the wake-up, showing superb endurance performance.

Impact of Hot Carrier Aging on the 1/f and Random Telegraph Noise of Short-Channel Triple-Gate Junctionless MOSFETs

The low-frequency noise of short channel triple-gate junctionless (TG JL) MOSFET has been investigated in the frequency and time domains before and after hot carrier aging (HCA). The objective of this work is to investigate the interaction between HCA/flicker noise (1/f noise) and random telegraph noise (RTN) of short channel length device (L = 25 nm) exhibiting high density of interface traps. Significant variation in the noise spectral density has been observed between the fresh and the stressed device, related to the occurrence of generation-recombination (g-r) noise. Gate voltage dependence of g-r noise has been observed, assigned to gate dielectric traps and interface traps. In the fresh device, the noise is dominated by 1/f noise and multiple level RTN due to interface traps. In the stressed device, the 1/f noise is overlaid by multiple level RTN due to traps in the gate dielectric and at the gate insulator-silicon interface. The multiple level RTN relative amplitude can be described by the generic carrier number with correlated mobility fluctuations model as for the two level RTN detected in long channel devices (L = 65 and 95 nm).

(Invited) Compact Model for Short-Channel Organic Thin-Film Transistors with Extension for Non-Quasistatic Circuit Simulation and Variability Analysis

We present a compact model for organic thin-film transistors (TFTs) that covers both below-threshold and above-threshold operation with a single charge-based current expression [1]. The effect of hopping transport is included by a power-law mobility model. Contact resistances for staggered and coplanar device structures (Fig. 1) are considered, which can be nonlinear in the case of work-function mismatch between contacts and organic semiconductor [2]. Short-channel effects in submicron transistors, such as threshold-voltage roll-off and drain-induced barrier lowering (DIBL), are included [3].From the expression for the accumulated channel charge, a closed-form model for the drain-current variability due to carrier-number and correlated mobility fluctuations has been derived, relating these statistical variations to the trap density in the channel [4].Furthermore, by applying a partitioning scheme, charges are explicitly attributed to the source and drain contacts, allowing the derivation of a charge-based capacitance model valid for quasi-static operation [5]. Charges in the gate-to-contact overlap regions have been included.Utilizing this device model in a transmission-line approach, a circuit simulation including non-quasistatic effects is possible [6]. In the circuit-simulation netlist, the TFT is replaced by a macro model consisting of a finite number of n single transistors, whereby each single transistor represents a section of the intrinsic channel capacitance and a segment of the intrinsic channel resistance. This model is able to capture the charging and discharging of the channel capacitance of each segment through the channel resistance of the adjacent transistors. In this way, the frequency dependence of the node-to-node capacitances of the full device is obtained.The compact model has been implemented in the hardware description language Verilog-A and verified using results of measurements performed on organic p-channel TFTs fabricated on flexible polyethylene naphthalate (PEN) substrates by stencil lithography (Figs. 2, 3). The TFTs consist of 25-nm-thick aluminum gate electrodes, a 5.3-nm-thick hybrid AlOx/SAM gate dielectric, 30-nm-thick gold (Au) source and drain contacts coated with a pentafluorobenzenethiol (PFBT) monolayer, and a 25-nm-thick vacuum-deposited layer of the small-molecule organic semiconductor DPh-DNTT [7,8]. The transmission-line approach has been verified with good accuracy by comparison with frequency-dependent admittance measurements and numerical simulations of the transient switching behavior of organic TFTs. For a transient analysis, the optimum number of segments required to achieve good agreement between the results from the model and those from TCAD simulations is approximately n=6.In conclusion, the model presented here is fully capable of providing accurate results in dc, small-signal ac, and transient circuit simulations, including short-channel effects. Furthermore, the same set of equations allows an estimation of the drain-current variability due to charge trapping. Acknowledgements: This project was funded by the German Federal Ministry of Education and Research ("SOMOFLEX", No. 13FH015IX6), German Research Foundation (DFG) under Grant KL 1042/9-2 (SPP FFlexCom), and EU H2020 RISE ("DOMINO", No. 645760). We acknowledge AdMOS GmbH, Germany for support.

Low-Frequency Noise Characteristics of Inkjet-Printed Electrolyte-Gated Thin-Film Transistors

Low-frequency noise is a critical characteristic of transistors, but there are only a few experimental works on the noise in printed electronics. In this work, we characterize the low-frequency noise of inkjet-printed electrolyte-gated thin-film transistors (EGTs) with indium-oxide semiconductors. We confirm that the carrier number fluctuation with correlated mobility fluctuation is the dominating noise generation mechanism. Also, we present the benchmark analysis on the noise level of various thin-film technologies. Notably, the extracted value of trap density near the insulator-channel interface is high, indicating an inferior quality of solution-processed and inkjet-printed thin-films. However, because of electrolyte-gating, the large areal gate capacitance compensates the negative effect of the high trap density, effectively reducing the flat-band voltage noise. As a result, the normalized drain current noise is considerably lower than solution-processed transistors and comparable with sputtered inorganic transistors with dielectric gating. This renders the electrolyte-gating approach useful in reducing the noise for printed/solution-based transistors, suitable for low-noise applications.

Mobility Fluctuations in a Normally-Off GaN MOSFET Using Tetramethylammonium Hydroxide Wet Etching

Low-frequency noise (LFN) performances are investigated in a normally-off GaN metal-oxide-semiconductor field-effect transistor (MOSFET) fabricated by utilizing the tetramethylammonium hydroxide (TMAH) wet etching. The normalized power spectral densities (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Id</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) are measured and perfectly matched with both the correlated mobility fluctuations (CMF) and Hooge mobility fluctuations (HMF) noise models. From the curves of (S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Id</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) dependent on the gate overdrive voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> - V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , it is also confirmed that the mobility fluctuations prevail in the fabricated GaN device. The calculated Hooge constants (α <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</sub> ) according to the (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> - V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) are obtained to be 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ~ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> . The reason for the dominance of the mobility fluctuations and the relatively low α <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</sub> is attributed that the TMAH wet etching effectively removes the plasma etching damage and fully recovers the crystal quality of GaN channel.

Performance and Low-Frequency Noise of 22-nm FDSOI Down to 4.2 K for Cryogenic Applications

This work presents the performance and low-frequency noise (LFN) of 22-nm fully-depleted silicon-on-insulator (FDSOI) CMOS technology. The experimental measurements and the analysis are performed as a function of temperature for the first time, focusing on cryogenic applications, down to 4.2 K. The back bias impact on device performance is evaluated. The results reveal that the threshold voltage tuning is found to be temperature independent, allowing extra drain current improvement. This is particularly interesting for short channel devices, whose drain current gain with temperature lowering is expected to be smaller in comparison with long channel MOSFETs. LFN is characterized by means of time-domain current sampling measurements. Moderate and strong inversion regimes are investigated. The carrier number with correlated mobility fluctuations model can well describe the 1/f noise behavior down to 4.2 K. The physical origin behind the drain current noise-to-signal power augmentation with temperature lowering could be mainly attributed to the normalized transconductance improvement.