Generation-recombination Noise Research Articles

The enhanced characteristics of bipolar phototransistor with huge amplification

Heterojunction devices based on low-dimensional materials have the potential for convenient and efficient photodetection applications. In this study, we demonstrate a van der Waals (vdW) heterojunction device constructed by p-ZrGeTe4 and n-MoS2. Forming a p-n junction, the response speed of the device increased by 6 orders of magnitude compared to devices with individual MoS2. To further improve the responsivity of the device, a bipolar phototransistor (PTD) was prepared based on the p-n junction. The PTD achieves the photocurrent gain of almost 40. This PTD achieves high responsivity of 1.48 A W−1, and the corresponding specific detectivity can reach 3 × 1014 Jones in low frequencies. Under low frequencies, the noise of the device is dominated by generation–recombination noise; and as the frequency increases, it gradually becomes dominated by 1/f noise. The PTD is competitive in optoelectronics and promising in high-performance integrated devices.

Analysis of noise and its characteristics in avalanche photodiode

Avalanche photodiodes (APDs) produce noise during operation, which affects the device performance. However, the previous research on its noise is mainly theoretical analysis and is only reflected as optical noise. Therefore, according to the characteristics of APD material and the mechanism of noise generation, the main noise of the device is analyzed in this paper. First, the test method of noise in APDs is established, including testing of dark noise, optical noise, and multiplication noise in high frequency bands. The main noises in APDs are 1/f noise, thermal noise, shot noise, generation recombination noise, and multiplication shot noise, and shot noise is suppressed by Fermi–Dirac distribution and Coulomb action. Second, the reliability of APDs is evaluated by measuring and analyzing the noise parameters of the device through thermal aging experiments. It is concluded that the defects introduced by thermal aging can be reflected by the change in noise, which is consistent with the results in the literature. This method can comprehensively obtain the noise in APDs, which is helpful to improve the working efficiency, life, and reliability of the device.

A nanophotonic approach to signal-to-noise ratio of quantum dot infrared photodetectors with surface plasmonic excitation

A nanophotonic approach to the signal-to-noise ratio (SNR) of an InAs-based quantum dot infrared photodetector (QDIP) with surface plasmonic excitation is reported. A 100 nm-thick Au film, perforated with a 3.1 μm-period, 2-dimensional square array of holes, referred to as a metal photonic crystal (MPC), is employed as a plasmonic coupler for it. Under the irradiance on the MPC integrated atop the QDIP, the fundamental surface plasma wave (SPW) is excited along their interface at ∼10.3 μm in wavelength. It carries the near-field that interacts with the quantum dots (QDs) under the interface. Depending on the presence of the coupler, the QDIP generates two different current–voltage (I-V) characteristics; one from the QDs normally working without MPC and the other from those coupled to the SPW near-field with it. The two I-V’s unfold the signal and noise current of each case with photoconductive gain. In their relation, generation-recombination and shot noises which are correlated with the detector signal current are directly affected by the plasmonic coupling but other sources including thermal noise are not relevant to it. Relying on these differences, the I-V analysis allows the SNR of each case and shows ∼20× enhancement by the plasmonic coupling. It reveals that most of the noise current is attributed to thermal fluctuations inherent to the quantum confinement of the QDIP. The SNR lower than the quantum efficiency in plasmonic enhancement is addressed.

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.

Noise behavior in GaAs0.2Sb0.8/GaSb heterojunction Source-All-Around vertical Tunnel FET: A comprehensive study

This article offers a comprehensive noise analysis of a GaAs0.2Sb0.8/GaSb heterojunction Source-All-Around Vertical Tunnel FET (SAA-VTFET), examining generation-recombination (GRN), flicker (FN), and diffusion (DN) noise. It pioneers an investigation into noise behavior under the influence of interface traps, temperature variations, and frequencies. Analysis includes both output current noise power spectral density (Sid) and input voltage noise power spectral density (Svg). Furthermore, the sensitivity of noise PSD is noted to be maximum at lower Vgs (gate bias voltage), suggesting that trap-assisted tunneling (TAT) and Shockley-Read-Hall (SRH) recombination dominate over band-to-band tunneling in this region. For enhanced clarity, this study also includes an analysis of the impact of traps and temperature on both AC and DC characteristics.

Noise analysis of NC-GAAFET cylindrical nanowire with non-uniform interface trap charge

In this article, low to high frequency noise behavior analysis of negative capacitance gate-all-around field effect transistor (NC-GAAFET) MFIS structure Silicon Nanowire (SiNW) device, using Sentauras TCAD simulations, is investigated. The NC-GAAFET SiNW yields on current (ION) 5.31 times larger and off current (IOFF) is significantly reduced by ∼ 105 orders compared to baseline SiNW. The device exhibits an excellent switching ratio of 5.2 × 1014. Average subthreshold swing for the NC-GAAFET is 33 mV/dec compared to 64 mV/dec of baseline nanowire. The Negative-DIBL for the device is −20 mV/V which outshines earlier findings. Furthermore, the drain current noise power spectral density (PSD) Sid, and input referred gate voltage noise PSD (Svg) are comprehensively analyzed in the presence of Gaussian trap (non-uniform) distribution. The analysis indicates that, flicker or (1/f) noise dominates in low frequency regime, generation-recombination (G-R) noise is more influential in mid frequency regime whereas in very high frequency regime diffusion noise is leading. The device exhibits least Sid(NET) and Svg(NET) at tfe = 6 nm compared to baseline, tfe = 5 nm, and 7 nm.

Impact of interface traps and noise analysis on dual material graded channel CGAA FET: A device reliability

This paper explores the effects of changing the device's parameters, such as the gate length (Lg), nanowire radius (r), oxide thickness (tox), and frequency (f), on the noise characteristics of dual material graded channel (DMGC) cylindrical gate all around (CGAA) FET while considering the presence and absence of interface trap charges. The performance analysis of the DMGC CGAA FET with that of the SMGC (single material graded channel) CGAA FET, is carried out while taking into account the impact of trap charges. It's noteworthy that the DMGC FET demonstrates significant advantages, with improvement in Ion/Ioff, reduction in DIBL, and SS when compared to the SMGC CGAA FET, both in the cases of without and with traps. The investigation also extends to analyse the analog/RF performance of the DMGC FET, for different type of trap charges. Furthermore, the power spectral densities of current noise (Sid) and voltage noise (Svg) are examined by varying the device dimensions and temperature. This also addresses the various sources of noise, including flicker noise (1/f), generation-recombination (G-R) noise, and diffusion noise. These types of noise have different prevalence depending on the operating frequency. At low frequencies, flicker and G-R noises dominate, while at higher frequencies, diffusion noise becomes the prominent factor impacting the device's performance. The research findings indicate that the optimal performance of the DMGC CGAA FET is achieved with smaller nanowire radius and thinner oxide thickness, regardless of trap charges. These findings offer valuable insights for improving the design and performance of DMGC CGAA FET in low power applications.

Analysis of noise behavior and reliability of pocket doped negative capacitance FET under the impact of trap charges and temperature

This paper represents an in-depth investigation of low to high frequency noise performance of highly doped double pocket double gate NCFET (HDDP-DG-NCFET) and single gate NCFET (SG-NCFET) in the existence of Uniform and Gaussian trap charges at various frequencies and temperatures (200 K–400 K). The drain current noise spectral density (Sid) and Gate voltage noise spectral density (Svg) at different frequencies in existence of both type of trap charges are explored. In addition, the Sid as a function of frequency for various ferroelectric thicknesses (Tfe) is examined in the existence of Uniform trap charges. The findings show that, at lower frequencies flicker noise dominates, while at higher frequencies, the dominant noise element is diffusion noise. For the whole range of considered frequencies, the Generation-Recombination (G-R) noise is more substantial in existence of trap charges. It has been found that, the net Sid value of the HDDP-DG-NCFET for Uniform and Gaussian types of trap distribution is 6.98 × 10−14A2/Hz and 6.17 × 10−14A2/Hz, respectively. Moreover, the examination of Sid for various Tfe in presence of traps illustrates the significance of the ferroelectric layer in obtaining lower value of net Sid, particularly in the higher frequency region and the minimal net Sid value for Tfe = 7 nm as compared to other Tfe values. Finally, to examine the device's reliability, the temperature investigation for the noise in the non-existence and existence of trap charges demonstrates that, the impact of an increase in noise caused by the existence of trap charges is much pronounced at lower temperatures and smaller gate voltages, where G-R noise is observed to be the dominant noise component.

Quasiparticle Generation-Recombination Noise in the Limit of Low Detector Volume

We have measured the quasiparticle generation-recombination (GR) noise in aluminium lumped element kinetic inductors with a wide range of detector volumes at various temperatures. The basic detector consists of meandering inductor and interdigitated capacitor fingers. The inductor volume is varied from 2 to 153 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu \mathrm{m}^{3}$</tex-math></inline-formula> by changing the inductor width and length to maintain a constant inductance. We started with measuring the power spectrum density (PSD) of the detectors frequency noise which is a function of GR noise and we clearly observed the spectrum roll off at 10 kHz which corresponds to the quasiparticle lifetime. Using data from a temperature sweep of the resonator frequency we convert the frequency fluctuation to quasiparticle fluctuation and observe its strong dependence on detector volume: detectors with smaller volume display less quasiparticle noise amplitude. Meanwhile we observe a saturated quasiparticle density at low temperature from all detectors as the quasiparticle life time <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol{\tau _{qp}}$</tex-math></inline-formula> approaches a constant value at low temperature.

Noise Optimization for MKIDs With Different Design Geometries and Material Selections

The separation and optimization of noise components is critical to microwave-kinetic inductance detector (MKID) development. We analyze the effect of several changes to the lumped-element inductor and interdigitated capacitor geometry on the noise performance of a series of MKIDs intended for millimeter-wavelength experiments. We extract the contributions from two-level system noise in the dielectric layer, the generation-recombination noise intrinsic to the superconducting thin-film, and system white noise from each detector noise power spectrum and characterize how these noise components depend on detector geometry, material, and measurement conditions such as driving power and temperature. We observe a reduction in the amplitude of two-level system noise with both an elevated sample temperature and an increased gap between the fingers within the interdigitated capacitors for both aluminum and niobium detectors. We also verify the expected reduction of the generation-recombination noise and associated quasiparticle lifetime with reduced inductor volume. This study also iterates over different materials, including aluminum, niobium, and aluminum manganese, and compares the results with an underlying physical model.

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.

Electrical Noise Analysis of Z Shape Horizontal Pocket and Hetero Stack TFETs under Trap Distribution

In this work, a comprehensive investigation on noise analysis for two different low power devices, namely Z-shaped Horizontal Pocket (ZHP) and Hetero Stack (HS) TFETs, is presented within low to high frequency range. The simulation is performed for these structures in the presence of Uniform and Gaussian trap distributions at the interface of Silicon and oxide materials for three different noise namely Flicker noise, Generation Recombination (GR) noise, and Diffusion noise with the help of the Sentaurus TCAD simulator. The result reveals that Flicker and GR noise are dominates at Low Frequency, while, the diffusion noise reports significant influence at the high-frequency range. Finally, a comparative analysis has been done in terms of noise current spectral density (Sid) of the considered structures with the existing literature.

Generation–recombination noise in uniformly doped semiconductors with contacts of finite surface recombination velocities

The formula for the voltage noise spectrum due to generation–recombination (G–R) rate fluctuations is derived for uniformly doped majority-carrier n-type semiconductor samples with contacts of finite surface recombination velocities. In the derivation of the formula, a new boundary condition with finite surface recombination velocities considered is used instead of the ohmic boundary condition. The G–R voltage noise spectra are calculated to become saturated and equal in the high electric field region irrespective of surface recombination velocities. However, the behaviors of slow surface recombination velocities in the low electric field region differ from those of fast ones. The profiles of the electron density fluctuations of slow ones differ significantly from those of fast ones in the low-field region. In the high field region, a steep rise in the magnitude of the electron density fluctuation occurs near the voltage contact toward which electrons drift. The various location dependencies of the contribution of noise sources to the voltage power spectral density are also derived for low and high field regions as well as low and high surface recombination velocities, and analytical expressions are developed for the voltage power spectral densities and electron density fluctuations.

Low to high-frequency noise behavior investigation of steeper sub-threshold swing NC-GeFinFET

The role of noise effect, in presence of Gaussian-trap distribution on the negative capacitance germanium FinFET (NC-GeFinFET) by using Sentaurus-TCAD is investigated. Incorporation of ferroelectric FE-layer in NC-GeFinFET, ION boosts by almost 18% compared to the baseline FinFET. Also steeper sub-threshold swing (SS) of 7.4 mV/decade is achieved by using the FE-layer of thickness (tfe) 6 nm at the room temperature. Result reports how the 1f noise and Generation-Recombination (G-R) noise plays an important role in net drain current spectral density (net Sid) for the proposed device up to mid frequency range, and the diffusion noise dominates in the high frequency range. This study highlights the analysis of net Sid with respect to frequency for different tfe. The minimum net Sid value 4.45 ×10−16 A2/Hz is achieved at 10 Hz, in presence of Gaussian-trap, for tfe 6 nm and is compared with the results for tfe 4 nm and 5 nm. This shows the importance of FE-layer in achieving low net Sid, especially in high frequency regime.

Generation-recombination noise and other features of doped silicon in a wide temperature range

The characteristics of the generation-recombination (g-r) process in silicon are investigated in a temperature range from 25 to 360 K. In the case of shallow donors, it is shown that the free electron density strongly depends on temperature: only 20% of donors are ionized at shallow donor densities of about 1017 cm-3 at liquid nitrogen temperature. The maximum of the variance of generation-recombination noise due to the free electron density fluctuations for a silicon sample with shallow donors strongly increases with donor density and shifts with temperature. It is demonstrated that the relative variance of free electron number fluctuations is always equal to 0.5 at low temperatures. The normalized generation-recombination noise spectra are depicted in a very wide frequency range. There is also a detailed investigation of the generation-recombination noise characteristics of an acceptor-partially compensated silicon sample with two donor levels. In this work, the main focus is on the characteristics of silicon doped by shallow donors as it is extremely widely used.

Noise Processes and Nonlinear Mechanisms in Optoelectronic Phase-Locked Loop Using a Balanced Optical Microwave Phase Detector

This article analyses the effect of noise and nonlinearity in optoelectronic phase-locked loops (OEPLLs). The OEPLL phase-locks a microwave oscillator on the envelope of the optical pulse train from a mode-locked laser (MLL). The phase detector of this type of OEPLL is called a balanced optical microwave phase detector (BOMPD) and operates in a mixed electro-optical domain. The main noise sources in a BOMPD, such as shot noise of photodiodes, generation-recombination noise of photodiodes, relative intensity noise of the laser, and noise of the bias voltage applied to the BOMPD. are discussed. The nonlinear behavior of the BOMPD with respect to the intensity of the optical field and the amplitude of the RF voltage is discussed. An OEPLL that can lock on the harmonics and interharmonics of the MLL repetition rate is demonstrated. The OEPLL has an in-band phase noise of below −150 dBc/Hz at 100-kHz offset frequency for a carrier frequency of 10 GHz. This phase noise level is 10–20 dB better than state-of-the-art commercial frequency synthesizers.

(Electronics and Photonics Division Award) The Impact of Defects on the Performance of Semiconductor Devices and Materials

Since the early days of the semiconductor industry, defect control has been key to the successful development of devices and circuits. It requires a thorough understanding of their formation and the impact on the electrical material parameters. This has only been possible by the invention of powerful structural, chemical and electrical characterization tools, with the device itself perhaps as the most sensitive probe. This evolution was paralleled by the development of ab initio calculation methods, based on Density Functional Theory and more recently, also TCAD tools allowing more and more refined modelling of the impact of defects on the electrical characteristics of devices.The implementation of other materials than Si and SiO2 in CMOS through the hetero-epitaxial growth on a silicon substrate for example, has renewed the interest in defect engineering during the last two decades, leading to single-defect analysis methods like Random Telegraph Noise (RTN) [1] or novel growth schemes like Aspect Ratio Trapping (ART) [2] for the removal of extended defects from the device active regions.In this presentation, some state-of-the-art analysis techniques will be highlighted, including Deep Level Transient Spectroscopy (DLTS) [3], Generation-Recombination (GR) noise and RTN spectroscopy [1,4] and p-n diode lifetime analysis [5]. These methods will be applied to several case studies. As shown in Fig. 1, threading extended defects impact the recombination lifetime of lowly-doped n-type In0.47Ga0.53As starting from a density of a few 107 cm-2. Likewise, it will be demonstrated that the GR noise observed in GaN-on-Si MOSHEMTs (Fig. 2) most likely originates from threading dislocations [6]. It is concluded that when hetero-epitaxial layers can be grown with a sufficiently low defect density, their impact will be more on the variability of the electrical parameters rather than on the effective values. In addition, the position of the defect with respect to strategic nodes like a p-n junction or depletion region largely determines its electrical impact, as has been validated by TCAD simulations.

Role of gate electrode in influencing interface trap sensitivity in SOI tunnel FETs

This article reports the response of a silicon-on-insulator tunnel field-effect transistor (TFET) to the presence of semiconductor/ gate dielectric interface traps. A systematic strategy is designed keeping in view different parameters which are related to the gate of the device. Acceptor-like traps, and donor-like traps with Gaussian distribution are considered at the said interface for the entire analysis. Sensitivity % is taken as a figure of merit which measures the deviation of the drain current in presence of traps from the cases with no traps. The effect of temperature on interface traps, and the effect of interface traps on gate leakage current are analyzed. The acceptor-like traps are found to affect the on-state regime, and the donor-like traps are found to affect the ambipolar regime. Analyses on gate–drain underlap, gate–source overlap, shift of entire gate over the device, and gate work-function suggest that the gate electrode plays an important role in determining the sensitivity of the TFETs. Furthermore, noise spectral densities in presence of flicker, diffusion, and monopolar generation-recombination noise sources, and interface traps are reported.

Excess noise in high-current diamond diodes

We report the results of an investigation of low-frequency excess noise in high-current diamond diodes. It was found that the electronic excess noise of the diamond diodes is dominated by the 1/f and generation-recombination noise, which reveals itself as Lorentzian spectral features (f is the frequency). The generation-recombination bulges are characteristic of diamond diodes with lower turn-on voltages. The noise spectral density dependence on forward current, I, reveals three distinctive regions in all examined devices—it scales as I2 at the low (I &amp;lt; 10 μA) and high (I &amp;gt; 10 mA) currents and, rather unusually, remains nearly constant at the intermediate current range. The characteristic trap time constants, extracted from the noise data, show a uniquely strong dependence on current. Interestingly, the performance of the diamond diodes improves with the increasing temperature. The obtained results are important for the development of noise spectroscopy-based approaches for device reliability assessment for high-power diamond electronics.

Terahertz superconducting kinetic inductance detectors demonstrating photon-noise-limited performance and intrinsic generation-recombination noise

Terahertz superconducting kinetic inductance detectors demonstrating photon-noise-limited performance and intrinsic generation-recombination noise