Large Leakage Current Research Articles

Super High-k Unit-Cell-Thick α-CaCr2O4 Crystals.

High-dielectric-constant (high-k) insulators are indispensable components to integrate semiconductors into metal-oxide-semiconductor field-effect transistors with sub-10 nm channel length, where the equivalent oxide thickness (EOT) of high-k insulator needs to be decreased to subnanometer scale. The traditional insulators, including Al2O3, SiO2, and HfO2, fit well with the existing silicon industry but suffer from serious degeneration of insulating properties, such as large leakage currents caused by high-density borders and interface traps, when their thicknesses are reduced to a few nanometers. Here, we synthesize a high-quality nonlayered ultrathin α-CaCr2O4 crystal down to unit-cell thickness (∼1.2 nm) by an elements slow-supply chemical vapor deposition (CVD) method. The unit-cell-thick α-CaCr2O4 crystals show a super high dielectric constant of 87.34, which is over 20 times higher than that of well-known layered insulator h-BN and corresponds to an EOT below 1 nm. Furthermore, it has a high breaking strength (39 GPa) and excellent stability. This strategy can also be used to fabricate other ultrathin ternary oxides, such as high-k ultrathin FeNb2O6 crystals, demonstrating the universality of the CVD method.

Enhancement of ferroelectric properties of the Ga0.6Fe1.4O3 films by Zn,N co-doping

Multiferroic materials have attracted considerable interests due to their scientific and technological importance in advanced devices. Ga0.6Fe1.4O3 thin film exhibits ferrimagnetism above room temperature but suffers from large leakage current. To reduce the charge conduction and enhance the ferroelectric properties of Ga0.6Fe1.4O3 film, ion doping is a useful technique. In this study, we fabricated Ga0.6Fe1.4-xZnxO3/N films by substituting Zn2+ and N3- ions in Ga0.6Fe1.4O3 for Fe and O, respectively. The influence of Zn, N co-doping on the structure, leakage current, magnetic and ferroelectric properties of the films were investigated. The results indicated that the films exhibited the orthorhombic structure with the incorporation of Zn and N. All Ga0.6Fe1.4-xZnxO3/N films showed above room temperature ferrimagnetism, and the magnetization and transition temperature values decreased with Zn,N co-doping. The microscopic and macroscopic ferroelectric measurements have demonstrated the ferroelectric polarization switching of the films. The ferroelectric hysteresis loops of the Ga0.6Fe1.38Zn0.02O3/N film showed the remnant polarization of ∼0.46 μC/cm2 with the coercive field of ±2 V at room temperature. The leakage current significantly reduced from ∼3.27×10−1 A/cm2 for pure Ga0.6Fe1.4O3 film to ∼1.48×10−5 A/cm2 for Ga0.6Fe1.35Zn0.05O3/N film, by four orders of magnitude. This may be attributed to the incorporation of Zn2+ and N3-, providing charge compensation to valence fluctuations of Fe between Fe3+ and Fe2+. These results provide an effective method to improve the ferroelectricity of Ga0.6Fe1.4O3 film, and open a wide perspective for the potential application in magnetoelectric devices.

Enlargement of effective area in Schottky barrier diodes on heteroepitaxial (001) diamond substrates by defect reduction and their radiation tolerance

A major obstacle to realizing diamond electronics is the presence of device-killing defects. Characteristics of diamond-based diodes are degraded with increasing contact size, and a large Ohmic-like leakage current can be generated. Here, we introduced a buffer layer to suppress the killer defects, which extended from the substrate to the epitaxial layer. With the utilization of the buffer layer created using the metal-assisted termination (MAT) technique, Schottky barrier diodes (SBDs) with diametric sizes of Schottky contact ranging from 65 to 1000 μm were fabricated on heteroepitaxial-grown diamond (001) substrates. The SBDs exhibited an explicit rectifying behavior with a rectification ratio of >1010 even with 1000 μm circular contact (7.85 × 10−3 cm2). Satisfying diode parameters were obtained with an ideality factor of 1.52, a Schottky barrier height of 1.66 eV, and a picoampere of leakage current at a reverse bias of 10 V. Interestingly, the diode parameters of the diamond-based SBDs such as ideality factor, Schottky barrier height and rectifying ratio were likely not changed or degraded even after absorption to 1 MGy in the dose of white X-ray. Overall, this demonstration indicates a promising way to realize a large active area of diamond electronics that is applicable to high-output power transmission devices and detector applications.

Tracking intrinsic ferroelectric switching under electric field via operando second harmonic generation

Polarization hysteresis is the defining characteristic of ferroelectrics, though the measurement of ferroelectric hysteresis is often complicated by artifacts such as leakage current and not all materials with apparent electrical hysteresis are ferroelectric. In this Letter, we have set up an operando second harmonic generation (SHG) system to track intrinsic ferroelectric switches under electric field, which is free from leakage current interference, thus yielding a signature for intrinsic ferroelectricity. Taking representative PbZr0.2Ti0.8O3 (PZT) thin films with different thicknesses as examples, the operando SHG system can capture ferroelectric hysteresis not only for PZT films thicker than 50 nm, for which conventional hysteresis measurement works, but also for PZT film as thin as 26 nm, for which conventional measurement fails due to the presence of large leakage current. Different domain evolution processes in these films are also illustrated.

High-performance MoS2 phototransistors with Hf1–x Al x O back-gate dielectric layer grown by plasma enhanced atomic layer deposition

Molybdenum sulfide (MoS2) as an emerging optoelectronic material, shows great potential for phototransistors owing to its atomic thickness, adjustable band gap, and low cost. However, the phototransistors based on MoS2 have been shown to have some issues such as large gate leakage current, and interfacial scattering, resulting in suboptimal optoelectronic performance. Thus, Al-doped hafnium oxide (Hf1–x Al x ) is proposed to be a dielectric layer of the MoS2-based phototransistor to solve this problem because of the relatively higher crystallization temperature and dielectric constant. Here, a high-performance MoS2 phototransistor with Hf1–x Al x O gate dielectric layer grown by plasma-enhanced atomic layer deposition has been fabricated and studied. The results show that the phototransistor exhibits a high responsivity of 2.2 × 104 A W−1, a large detectivity of 1.7 × 1017 Jones, a great photo-to-dark current ratio of 2.2 × 106%, and a high external quantum efficiency of 4.4 × 106%. The energy band alignment and operating mechanism were further used to clarify the reason for the enhanced MoS2 phototransistor. The suggested MoS2 phototransistors could provide promising strategies in further optoelectronic applications.

Enhancing photo and X-ray detection performance of (BDA)CsPb2Br7 perovskite single crystals by removing surface defects

Two-dimensional (2D) hybrid perovskite single crystals are promising photovoltaic materials. However, the single crystals grown from solution usually respond poorly to light and other charged particles. The 2D (BDA)CsPb2Br7 single crystals (BDA = 1,4-butanediamine) are grown from a supersaturated solution. The macroscopical growth steps are present on the surface, leading to a large leakage current during device operation. The surface defects are removed to expose a clean and flat surface. This well-defined crystallographic surface enables an Ohmic contact with the electrode, which minimized the dark current and baseline drift. Consequently, the assembled devices exhibit an enhanced response to LED light and X-rays, revealing the surface defect to be one of the culprits underneath the poor performance of solution-grown perovskite single crystals.

Enhanced resistivity and piezoelectric response in BiFeO3-BaTiO3 via two-step sintering

Due to the defects from Bi volatilization and Fe ion valence change during normal sintering (NS), the BiFeO3-BaTiO3 (BF-BT) ceramic is always accompanied by serious leakage current and deteriorated electrical performance, which impeded its further application. In this work, the two-step sintering (TSS) method was applied to the BF-BT ceramics preparation, and numerous microstructures of samples were observed and verified that it can decrease the sintering temperature from 1000 ℃ to 900 ℃ and enhance the relative density to above 96%. This reduced the defects and solved the issue of large leakage current, and the resistivity of TSS samples is an order of magnitude higher than NS samples and reaches the maximum among the already reported. Moreover, the experimental and theoretical results conclude that the TSS samples obtained a stronger intrinsic piezoelectric effect, which increased the strain from 0.13% to 0.19%. The TSS method displayed enormous potential for BF-BT preparation.

Enhanced ferroelectric and magnetic properties of the 0–3 type BiFeO3-BaTiO3/BaFe12O19 composite multiferroic material

The 0–3 type (1-x)(0.75BiFeO3-0.25BaTiO3)/xBaFe12O19 (BFO-BTO/BaM) multiferroic composites were successfully prepared by a solid-state reaction sintering process. The coexistence of perovskite BFO-BTO phase and hexagonal BaM phase was confirmed for all BFO-BTO/BaM composites. Due to the large leakage current, the breakdown electric field decreased with increasing BaM content. Nevertheless, the ferroelectric properties of the composite ceramics have also been significantly improved, mainly as the increase of remanent polarization and the decrease of coercive field, where Pr = 19.79 μC/cm2, Ec = 30 kV/cm at x = 0.075. Meanwhile, the magnetic properties of BFO-BTO phase were enhanced, and the remanent magnetization linearly increased with increasing BaM content. The single domain magnetic structure was obtained for all BFO-BTO/BaM composite ceramics, and the magnetic properties changed after electric poling, which indicated the electric field controlled magnetic properties. The electric-controlled magnetic behavior was attributed to the structural phase transition. The magnetoelectric coupling coefficient αME of the composite material has been improved, with a maximum value of 0.61 mV/cm.Oe. Thus, the BFO-BTO/BaM magneto-electric composite system is a promising multiferroic system in information technology and sensing fields.

Correlations between reverse bias leakage current, cathodoluminescence intensity and carbon vacancy observed in 4H-SiC junction barrier Schottky diode

Reverse bias currents of ten commercial junction barrier Schottky diodes were measured, and the dies were studied by scanning electron microscope (SEM) and cathodoluminescence (CL) after the de-capsulation of the diodes. Defect emissions (DEs) of 2.62 eV were observed in all the CL spectra. By comparing the SEM images, the integral CL intensity spatial mappings and the reverse bias leakage currents, correlations between the leakage current, the integral CL intensity and the Al-implantation process were established. The data of reverse bias leakage current against the reverse bias voltage taken at room temperature followed the Poole Frenkel emission from the Z 1/Z 2 carbon vacancy states to the conduction band. The DE at 2.62 eV is associated with the electronic transition from Z 1/Z 2 to the valence band. The current observation also opens up the feasibility of screening off SiC diodes with large leakage current during production by inspecting the CL intensity before the device fabrication is complete.

Great enhancement of ferroelectric properties of Al2O3-modified BiFeO3 thin films obtained by sol-gel method

Thin films prepared by sol-gel method usually have a large leakage current, which hinders their practical applications. Therefore, it is extremely important to adopt effective strategies to reduce their leakage current. In this work, BiFeO3 thin films with Al2O3 modification, either in the format of layer insertion or evenly-distributed particles incorporation, are fabricated by a sol-gel method on the Pt(111)/Ti/SiO2/Si substrates. It was found that an optimal amount of Al2O3 in the system can greatly compress the leakage current and enhance the ferroelectric properties. For BiFeO3 films with thickness in the ∼300 nm range, remnant polarization (Pr) of ∼ 40.82, 80.08, 61,6 μC/cm2, and maximum polarization (Pmax) of ∼ 62, 157, 90 μC/cm2 can be achieved for Al2O3 modification via 1/3, 1/5 layer insertion and 1:5 particle incorporation, respectively. Additionally, we systematically investigated the impact of Al2O3 on the phase microstructure, leakage current, and conduction mechanism behavior of Al2O3-modified BiFeO3 films. The results not only promote the sol-gel method as a promising method for preparing high-quality ferroelectric thin films with compressed leakage, but also promote the potential applications of BiFeO3 thin films in electromechanical devices.

(Digital Presentation) Improvement of the Compatibility between the Current-Independent Constant Voltage Loss in Wagner’s Equation for SOFCs Using Sm-Doped Ceria Electrolytes and Jarzynski’s Equality

A solid oxide fuel cell (SOFC) converts chemical energy from a fuel gas, such as hydrogen or methane, to electrical energy. Yttria-stabilized zirconia (YSZ) films are often used as electrolytes, in which only oxygen ions are carriers. In such cases, the open-circuit voltage (OCV = 1.15 V at 1073 K) is equal to the Nernst voltage (Vth = 1.15 V at 1073 K).Samaria-doped ceria (SDC) has higher ionic conductivity than YSZ. Therefore, SDC films are possible electrolyte candidates. However, when SDC electrolytes are used in SOFCs, the OCV at 1073 K is only 0.80 V. The voltage loss has been explained by Wagner’s equation.Numerous subsequent models have been created based on Wagner’s equation. The current-voltage relationship can be calculated with the cathode and anode polarization voltage losses using the Riess model [1]. Furthermore, Duncan and Wachsman created a nonlinear model [2]. This model can also be used to explain the equilibration process. According to the Riess model, the OCV should decrease during electrode degradation. However, experimentally, the OCV does not change during electrode degradation [3]. The change in the equilibration of thick SDC electrolytes in response to a change in the anode gas has never been explained using the model of Duncan and Wachsman. Experimentally, when a very thick (6.6 mm) SDC electrolyte is used, the OCV can reach 0.80 V in only 5 minutes [4]. According to Weppner, the corresponding delay in the electron diffusion current should be more than 2080 minutes [5].We proposed a current-independent anode voltage loss (0.35 V = 1.15 V- 0.80 V) [6]. Since we disproved the existence of large leakage currents in SDC electrolytes, our explanations seem to disregard and disprove Wagner’s equation. However, we noted that the dismissal of the idea of large leakage currents in SDC electrolytes is only a side effect. When SDC electrolytes experience a large anode voltage loss (0.35 V), the leakage currents are very small. This phenomenon is called the “anode shielding effect” [7].The ionic activation energy (Ea) of SDC electrolytes is 0.7 eV (= 0.35 V ×2e). During ion hopping processes in SDC electrolytes, the work done by ions on the surrounding lattice structure is 0.7 eV. The ions should regain 0.7 eV after hopping. However, when there are many electrons in the hopping path, the hopping processes are very complex, and calculating the work loss is challenging [8].Jarzynski’s equality is very useful for calculating the Gibbs energy loss at the nanoscale. One ion hopping process in SDC electrolytes is at the nanoscale. However, the number of oxygen ions in SDC electrolytes is on the order of 1021, which is near Avogadro’s number. The number of oxygen ions that can participate in the hopping process is on the order of 1016 at 1073 K. Furthermore, the average frequency of the oxygen ions is 1013 Hz. Consequently, we are discussing an average Gibbs energy loss on the order of 1029 in one second. This means that our model is much more statistical as follows. Jarzynski’s equality ⊇ Our model (OCV = Vth -Ea /2e) (1) Fortunately, the canonical ensemble for the ion hopping process follows Boltzmann's distribution, which is an exponential distribution and determined only by the temperature of the environment. We try to improve the compatibility between the current-independent constant voltage loss in Wagner’s equation for SOFCs using SDC electrolytes and Jarzynski’s equality.

Non-volatile reconfigurable spin logic functions in a two-channel Hall bar by spin–orbit torque-based magnetic domains and directional read current

A long-standing goal of CMOS-based logic devices is to meet the needs of key markets, including ultralow-power operation and high operation speed, along with the continuing miniaturization of the architecture. However, despite significant progress in their development, conventional CMOS-based devices still suffer from drawbacks such as introducing large unintended leakage currents and volatile behavior. Thus, reconfigurable logic gates based on magnetic domain (MD) have emerged as a highly promising option because they offer fast operation speeds, nonvolatility, and diverse logic functions in a single-device configuration. Here, we address multiple reconfigurable MD logic gates in a single two-channel Hall bar device by varying the voltage-driven read-current directions and selecting a non-inverting or inverting comparator in W/CoFeB/MgO/Ta stacks. The non-volatile MD switching behavior induced by spin–orbit torque significantly affects our logic gate functions, which are not necessarily synchronized to a single clock. By adapting MD switching by spin-orbit torque and anomalous Hall effect voltage outputs, we identified eight reconfigurable logic gates, including AND, NAND, NOR, OR, INH, Converse INH, Converse IMP, and IMP, in a single device. These experimental findings represent a significant step forward in a wide range of MD-based logic applications in the near future.

Contact-engineered reconfigurable two-dimensional Schottky junction field-effect transistor with low leakage currents

Two-dimensional (2D) materials have been considered promising candidates for future low power-dissipation and reconfigurable integrated circuit applications. However, 2D transistors with intrinsic ambipolar transport polarity are usually affected by large off-state leakage currents and small on/off ratios. Here, we report the realization of a reconfigurable Schottky junction field-effect transistor (SJFET) in an asymmetric van der Waals contact geometry, showing a balanced and switchable n- and p-unipolarity with the Ids on/off ratio kept >106. Meanwhile, the static leakage power consumption was suppressed to 10−5 nW. The SJFET worked as a reversible Schottky rectifier with an ideality factor of ~1.0 and a tuned rectifying ratio from 3 × 106 to 2.5 × 10−6. This empowered the SJFET with a reconfigurable photovoltaic performance in which the sign of the open-circuit voltage and photo-responsivity were substantially switched. This polarity-reversible SJFET paves an alternative way to develop reconfigurable 2D devices for low-power-consumption photovoltaic logic circuits.

Efficacy of back barrier engineered Π-gate InAlN/GaN high electron mobility transistors for high-power applications

This work investigates thin-barrier InAlN/GaN high electron mobility transistors (HEMTs) for high-power applications through technology computer-aided design (TCAD) simulations. To begin with, the TCAD simulations were first calibrated with an in-house fabricated InAlN HEMT sample for both DC and pulsed characteristics. The thin-barrier InAlN/GaN HEMTs showed a large leakage current through the gate electrode due to high gate injection, which severely degrades the breakdown characteristics of the device and thus acts as a bottleneck for high-power applications. To improve the two-dimensional electron gas confinement, and consequently reduce the bulk leakage, a back-barrier technique was used. The resistive GaN buffer was replaced with an AlGaN back-barrier that improved the breakdown characteristics at the cost of output power density. Thus, to scale up the output power density and further optimize the breakdown characteristics a Π-shaped gate was introduced to limit the gate leakage current through the InAlN barrier by virtue of its improved hot electron reliability. Coupled with the AlGaN back-barrier, the Π-gate significantly improved the breakdown characteristics to achieve high output power densities, albeit with minor trade-offs to the device gain. To elucidate the compatibility with high-power applications, all the device architectures were dynamically characterized by pulsed I–V simulations and the trap-related dispersive effects were investigated. The Π-shaped gate coupled with an AlGaN back-barrier outperforms conventional architectures by exercising superior electrostatic control over the channel and exhibiting a high linearity for high-power millimeter-wave applications.

Defect‐Hydrogen Interactions in Top‐Anode Oxide Semiconductor Schottky Barrier Diode

AbstractAs amorphous oxide semiconductors (AOSs) are hotly pursued for advanced displays, flexible electronics, optoelectronics, and neuromorphic systems, the AOS Schottky barrier diodes (SBDs) have been tried only using the mainstream amorphous InGaZnO (a‐IGZO) and the conservative bottom‐anode structure. To deepen the study on AOS SBDs, the more challenging top‐anode SBD is developed in this work using a versatile but vulnerable AOS, amorphous InZnO (a‐IZO). Unsurprisingly, the Schottky interface defects are seriously increased by the top‐anode process and the defective a‐IZO, which cannot be effectively passivated using the incumbent oxidizing treatments. The hydrogenation is proposed to considerably suppress these annoying interface defects and thus correspondingly reduces the large leakage current, while the hydrogen doping easily deteriorates a‐IGZO SBD. The underlying mechanism of such distinction is revealed to be the tricky interactions between defect and hydrogen in AOSs. Based on the sophisticated utilization of such defect‐hydrogen interplay, the a‐IZO/a‐IGZO stack is hydrogenated together to simultaneously realize a high‐conductivity bulk and low‐defect interface, noticeably enhancing the performance metrics. Such top‐anode SBD based on hydrogenated multilayer AOSs successfully blazes a novel evolution path for AOS SBDs.

Remarkably Enhanced Charge Density of Inorganic Material Via Regulating Contact Barrier Difference and Charge Trapping for Triboelectric Nanogenerator

AbstractCurrently, the research on improving charge density of charge‐excitation triboelectric nanogenerators (CE‐TENG) mainly focuses on surface modification and thinning of organic polymer materials. However, to increase durability and output, the exploration of high permittivity and high‐thickness inorganic materials is important for extensive applications. Meanwhile, the physical mechanism of air ionization caused by air breakdown during secondary self‐charge excitation (SSCE) needs to be explored. Herein, this study proposes a new strategy for CE‐TENG based on inorganic materials by de‐trapping reverse charge and increasing the contact barrier difference to obtain high charge density and achieve secondary self‐charge excitation. SSCE of three types of films with different leakage currents are evaluated according to their trapping and de‐trapping reverse charges. It is found that the trap distribution of dielectric films with larger leakage currents are mostly shallow‐level traps, whose de‐trapping ability becomes stronger after reverse charge injection. By regulating the contact barrier difference with thin organic polymer on thick inorganic high permittivity material, this study has achieved a high charge density of 1310 µC m−2 with a fast start‐up time of SSCE, which is a new record for the charge density of inorganic materials. This study promotes TENG of inorganic materials toward high‐energy output applications.

Ultra-Low-Power Compact Neuron Circuit with Tunable Spiking Frequency and High Robustness in 22 nm FDSOI

Recent years have seen an increasing popularity in the development of brain-inspired neuromorphic hardware for neural computing systems. However, implementing very large scale simulations of neural networks in hardware is still an open challenge in terms of power efficiency, compactness, and biophysical resemblance. In an effort to design biologically plausible spiking neuron circuits while restricting power consumption, we propose a new subthreshold Leaky Integrate-and-Fire (LIF) neuron circuit designed using 22 nm FDSOI technology. In this circuit, problems of large leakage currents and device mismatch are effectively reduced by deploying the back-gate terminal of FDSOI technology for a tunable design. The proposed neuron is able to operate in two spiking frequency modes with tunable bias parameter setting of key transistors, and it results in complex firing behaviors, such as adaptation, chattering, and bursting, through varying bias voltages. We present circuit post-layout simulation results and demonstrate the biologically plausible neural dynamics. Compared with published state-of-the-art neuron circuits, the circuit dissipates ultra-low energy per spike, on the order of femtojoules per spike, at firing rates ranging from 30 Hz to 1 kHz. Furthermore, the circuit is proven to maintain a good robustness over process variation and Monte Carlo analysis, with relative error 3.02% at a firing rate of approximately 67.1 Hz.

2D semimetal with ultrahigh work function for sub-0.1 V threshold voltage operation of metal-semiconductor field-effect transistors

Metal-semiconductor field-effect transistors (MESFETs) offer the advantages of efficient gate control and low power consumption due to the large junction capacitance. However, the strong Fermi-level pinning caused by the metal-induced gap states makes it a great challenge to build a high-quality Schottky junction with a large energy barrier and low leakage current. Moreover, the upper limit of the work function of conventional metals is around 5 eV, which prevents the formation of a wide depletion region and the reduction of power consumption. In this work, 2D semimetals with high work function have been used as the gate to fabricate 2D van der Waals MESFETs. Compared with PtSe2 and PdSe2, TiS2 with ultrahigh work function of 6.6 eV forms the largest Schottky barrier height with MoS2. And TiS2/MoS2 MESFETs display a sub-0.1 V threshold voltage owing to the large built-in potential and exhibit a small subthreshold swing of 73 mV/dec. The tuning of the channel carrier density from the back gate can further optimize the device performance and provide a strategy to build AND logic gate in a dual-gated transistor. Our work successfully demonstrates the use of high-work-function 2D semimetal to realize high-performance MESFET with low power consumption.

Structural tailoring enables ultrahigh energy density and charge–discharge efficiency of PAEK copolymer dielectrics at high temperatures

High-temperature film capacitors have great potential for high-power-density applications, in which polymer films are often utilized as energy-storage dielectrics. However, their application in film-capacitor dielectrics is hindered by their large leakage currents at high temperatures, which leads to low energy density (Ue) and low charge–discharge efficiency (η). Here, a structural-tailoring strategy is demonstrated to suppress the high-temperature leakage currents of polyaryletherketone (PAEK) copolymers. For this purpose, a novel functional monomer containing benzimidazole and pyridine groups (BBP) was synthesized and the corresponding cross-linked c-P(AEK-BBP) dielectric films were successfully to prepared. Thanks to the introduction of the BBP units and the cross-linked network, the leakage current of c-P(AEK–BBP) is suppressed by nearly two orders of magnitude at 150 °C. This dielectric film exhibits 7.3 J·cm−3 under 600 MV·m−1 and 150 °C, which is superior to current state-of-the-art heat-resistant dielectric polymers.

A Charge Sensitive Amplifier in a 28 nm CMOS Technology for Pixel Detectors at Future Particle Colliders

This paper is concerned with the design of a Charge Sensitive Amplifier (CSA) in a 28 nm CMOS technology. The CSA discussed in this work is conceived for High Energy Physics (HEP) experiments at next-generation colliders, where pixel detectors will be read out by specific front-end chips, typically including a CSA exploited for charge-to-voltage conversion of the signal delivered by the sensor. The main analog performance parameters of the CSA, also referred to as the pre-amplifier, are assessed here by means of specific Spectre simulations, which are meant to evaluate the behavior of the analog processor in terms of noise, linearity and capability to compensate for very large detector leakage currents. Noise simulations revealed an equivalent noise charge close to 75 electrons rms for typical operating conditions. Up to 50 nA sensor leakage current can be compensated for thanks to the CSA Keummenacher feedback network. The total current consumption of the CSA is close to 2.2 µA, which, together with a power supply of 0.9 V, translates to a power consumption of 2.0 µW.