Degradation Of Electrical Performance Research Articles

Impact of High-Temperature Forward Bias Stress on the Electrical Performance Degradation of β-Ga₂O₃ Schottky Barrier Diodes

Impact of High-Temperature Forward Bias Stress on the Electrical Performance Degradation of β-Ga₂O₃ Schottky Barrier Diodes

A multi-objective configuration optimization method of passive hybrid energy storage system for pulse loads operating under very low temperatures

The lithium-ion battery energy storage system currently widely used faces a problem of rapid degradation of electrical performance at very low temperatures (such as −40 °C), making it difficult to meet the power supply requirements of high-power pulse loads in low-temperature environments. To address this issue, this paper proposes a multi-objective configuration optimization method for passive lithium-ion battery-supercapacitor hybrid energy storage systems (HESS) based on an electro-thermal-aging coupling model, in order to achieve non-preheating power supply for pulse loads under low temperatures. Firstly, an electro-thermal-aging coupling model for the passive HESS is established to accurately describe the dynamic characteristics during discharge. Subsequently, aiming at the low-temperature application requirements of high-power pulse loads, a multi-objective configuration optimization model is established based on the coupling model with the objectives of minimizing the mass and the minimum operating ambient temperature of the HESS; a solving method of the optimization model is designed based on the non-dominated sorting genetic algorithm with elite strategy. Finally, a case study is conducted on configuration optimization for a certain type of pulse load. The optimization results show that when the minimum operating temperature is consistent and below 0 °C, the passive HESS compared with the lithium-ion battery energy storage system can reduce the system mass by more than 23% and the acquisition cost by more than 18% while maintaining basically consistent single-pulse costs. When the minimum operating temperature is lower, the advantages of the HESS are even more significant.

Impact of low-temperature and low-pressure mild oxidation after plasma solidification on electrical properties and reliability in ultra-thin SiON MOSFETs

The impact of different SiON manufacturing processes on performance and reliability behaviors has been investigated for the MOSFETs. The performance of devices composed of an ultrathin SiON film fabricated by the novel low-temperature and low-pressure mild oxidation after the plasma solidification (LLMOPS) method can be enhanced compared to conventional processes, which is attributed to the increased mobility. It is observed from secondary ion mass spectrometry analysis that the distribution of nitrogen with the LLMOPS process moves toward the upper surface of SiON. As a result, the p-MOSFET manufactured by the LLMOPS process exhibits lower electrical performance degradation during the NBTI stress, indicating that a reduction in nitrogen concentration at the Si/SiO2 interface contributes to improving NBTI behavior. It is also demonstrated that the inhibition of NBTI phenomena enhances the frequency stability on the ring oscillator with circuit simulation. Thus, the LLMOPS process is a promising approach to improve the performance and reliability of MOSFETs in mass production.

A highly stretchable smart dressing for wound infection monitoring and treatment

Smart dressings integrated with bioelectronics have attracted considerable attention and become promising solutions for skin wound management. However, due to the mechanical distinction between human body and the interface of electronics, previous smart dressings often suffered obvious degradation in electrical performance when attached to the soft and curvilinear wound sites. Here, we report a stretchable dressing integrated with temperature and pH sensor for wound status monitoring, as well as an electrically controlled drug delivery system for infection treatment. The wound dressing was featured with the deployment of liquid metal for seamless connection between rigid electrical components and gold particle-based electrodes, achieving a stretchable soft-hard interface. Stretching tests showed that both the sensing system and drug delivery system exhibited good stretchability and long-term stable conductivity with the resistance change rate less than 6 % under 50 % strain. Animal experiments demonstrated that the smart dressing was capable of detecting bacterial infection via the biomarkers of temperature and pH value and the infection factors of wound were significantly improved with therapy through electrically controlled antibiotics releasing. This proof-of-concept prototype has potential to significantly improve management of the wound, especially those with dynamic strain.

Effects of gamma-ray irradiation on material and electrical properties of AlN gate dielectric on 4H-SiC

This article investigates the radiation effects on as-deposited and annealed AlN films on 4H-SiC substrates under gamma-rays. The AlN films are prepared using plasma-enhanced-atomic-layer-deposition on an n-type 4H-SiC substrate. The AlN/4H-SiC MIS structure is subjected to gamma-ray irradiation with total doses of 0, 300, and 600 krad(Si). Physical, chemical, and electrical methods were employed to study the variations in surface morphology, charge transport, and interfacial trapping characteristics induced by irradiation. After 300 krad(Si) irradiation, the as-deposited and annealed samples exhibit their highest root mean square values of 0.917 nm and 1.190 nm, respectively, which is attributed to N vacancy defects induced by irradiation. Under irradiation, the flatband voltage (V fb) of the as-deposited sample shifts from 2.24 to 0.78 V, while the annealed sample shifts from 1.18 to 2.16 V. X-ray photoelectron spectrum analysis reveals the decomposition of O-related defects in the as-deposited AlN and the formation of Al(NO x ) y compounds in the annealed sample. Furthermore, the space-charge-limits-conduction (SCLC) in the as-deposited sample is enhanced after radiation, while the barrier height of the annealed sample decreases from 1.12 to 0.84 eV, accompanied by the occurrence of the SCLC. The physical mechanism of the degradation of electrical performance in irradiated devices is the introduction of defects like N vacancies and O-related defects like Al(NO x ) y . These findings provide valuable insights for SiC power devices in space applications.

Facile fabrication of layer-structured graphene/copper composite with enhanced electrical and mechanical properties

Copper (Cu) and its related composites are widely used and hence extremely important in industrial applications. Much efforts have been made to improve the physical properties of Cu, but usually lead to degradation of electrical performance. Herein, this work develops a facile way to fabricate layer-structured graphene/copper composite using graphene powder sprayed on Cu foil as building blocks. Compared to pure Cu bulk, significant improvement of both the electrical conductivity of 105.12% IACS and also ∼17% enhanced tensile strength is achieved. This strategy provides a versatile way to produce high-performance Cu composite in large with low cost for practical applications.

Degradation of electrical performance and radiation damage mechanism of cascode GaN HEMT with 80 MeV proton

In this paper, proton irradiations on Cascode GaN HEMT power device with an energy of 80 MeV and fluences of 2 × 1011 p/cm2 and 6 × 1011 p/cm2 have been carried out, where the threshold voltages drifted negatively by 20.55% and 28.17%, respectively. After two months of room temperature annealing, the threshold voltages recovered 0.22 V and 0.27 V, respectively. The ionizing deposition energy (IEL) was simulated by using Monte Carlo software and TCAD, it the results showed that the value of IEL in Si MOSFET is 5 ∼ 6 orders higher than that in GaN HEMT, while the value of the non-ionizing energy loss (NIEL) is one order higher than that in GaN HEMT. It means that the proton irradiation on the Cascode depleted GaN HEMT is more prone to produce displacement damage. As a large number of electrons and holes pairs were existed on the incident path of Si MOSFET under the proton irradiation, the produced electron will be captured by the gate oxide traps at the SiO2/Si interface, and the holes be captured by the defects generated in displacement damage, resulting in the accumulation of oxide trapped charges. Then, the electrical performance of Si MOSFET degrades seriously, thereby affecting the performance of the entire device. The studies will be helpful for the radiation hardening of Cascode GaN HEMT.

Two-temperature principle for evaluating electrothermal performance of GaN HEMTs

Self-heating effects in Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) can adversely impact both device reliability and electrical performance. Despite this, a holistic understanding of the relationship among heat transport mechanisms, device reliability, and degradation of electrical performance has yet to be established. This Letter presents an in-depth analysis of self-heating effects in GaN HEMTs using technology computer-aided design and phonon Monte Carlo simulations. We examine the differential behaviors of the maximum channel temperature (Tmax) and the equivalent channel temperature (Teq) in response to non-Fourier heat spreading processes, highlighting their respective dependencies on bias conditions and phonon ballistic effects. Our study reveals that Tmax, a crucial metric for device reliability, is highly sensitive to both heat source-related and cross-plane ballistic effects, especially in the saturation regime. In contrast, Teq, which correlates with drain current degradation, shows minimal bias dependence and is predominantly influenced by the cross-plane ballistic effect. These findings emphasize the importance of optimizing device designs to mitigate both Tmax and Teq, with a particular focus on thermal designs influenced by the heat source size. This work contributes to a deeper understanding of self-heating phenomena in GaN HEMTs and provides valuable insights for enhancing device performance and reliability.

Highly stretchable polymer semiconductor thin films with multi-modal energy dissipation and high relative stretchability

Stretchable polymer semiconductors (PSCs) have seen great advancements alongside the development of soft electronics. But it remains a challenge to simultaneously achieve high charge carrier mobility and stretchability. Herein, we report the finding that stretchable PSC thin films (<100-nm-thick) with high stretchability tend to exhibit multi-modal energy dissipation mechanisms and have a large relative stretchability (rS) defined by the ratio of the entropic energy dissipation to the enthalpic energy dissipation under strain. They effectively recovered the original molecular ordering, as well as electrical performance, after strain was released. The highest rS value with a model polymer (P4) exhibited an average charge carrier mobility of 0.2 cm2V−1s−1 under 100% biaxial strain, while PSCs with low rS values showed irreversible morphology changes and rapid degradation of electrical performance under strain. These results suggest rS can be used as a parameter to compare the reliability and reversibility of stretchable PSC thin films.

A cascaded Nitinol Langevin transducer for resonance stability at elevated temperatures

Across power ultrasonics and sensing, piezoelectric ultrasonic transducers commonly experience degradation in mechanical, electrical, and dynamic performance due to the relatively high sensitivity of piezoelectric materials to changes in temperature. These changes, arising for example through high excitation voltages or environmental conditions, can lead to nonlinear dynamic behaviours which compromise device performance. To overcome this, the excitation signal to the piezoelectric material is often pulsed, mitigating the influence of temperature rises. However, there remain constraints on suitable candidate piezoelectric materials for power ultrasonic devices. As a novel approach to mitigating the influence of temperature on the properties of piezoelectric materials, the phase-transforming shape memory alloy Nitinol is incorporated into the piezoelectric stack of a Langevin power ultrasonic transducer, in a cascade formation. The underlying principle is that the nonlinear hardening response of Nitinol to rising temperature can be used to dynamically compensate for the nonlinear softening of the piezoelectric materials. Thus, the dynamic response of the transducer can be linearised at elevated excitation levels. In this study, two configurations of Langevin transducer are designed and characterised. One transducer incorporates a Nitinol middle mass, and in the second, titanium. A combination of electrical and thermomechanical characterisation is undertaken, where it is demonstrated that the nonlinear softening of the piezoelectric stack can be mitigated through control of the Nitinol microstructure. The vibration amplitudes of the Nitinol-middle cascaded transducer are higher and more stable when the Nitinol is austenite rather than a combination of martensite and austenite at room temperature. It has also been shown that the vibration amplitude and resonance frequency of Nitinol-middle cascaded transducer remain stable as temperature changes from 20 °C to 45 °C, dependent of the excitation voltage. Moreover, the self-heating experiment demonstrates the resonance stability of the Nitinol-middle cascaded transducer for continuous operation.

Impact of RF stress on different topologies of 100 nm X-band robust GaN LNA

In this article, we study the robustness of 3 versions of a single stage LNA configured according to different modes of detectivity or robustness against electromagnetic jamming signals. Four successive sequences of RF step stress at 10 GHz are applied to each of the 3 LNAs under study. These robust MMIC LNAs have been designed using the D01GH GaN process from OMMIC technology, to switch from a nominal low noise mode to a high linearity mode. This DC-bias switch allows increasing the power input 1 dB compression point by 8 dB. This study focuses on the robustness of these LNAs (LNA#A for agile) when they operate under nominal low-noise mode (featuring lower IP1dB) or under nominal high-linearity mode (at the price of a degraded noise figure NF50). This original LNA#A is compared to a robust conventional design using a larger sized device (LNA#R for robust). The step-stresses are operated at 10 GHz, which is the center frequency band of these LNAs. All modes of operation are shown to exhibit fairly reproducible step stress plots, although thermal or nonlinear effects can be differentiated between low-noise and high-linearity operating conditions, and compared with the robust design LNA#R. We demonstrate the relevance of an alternative approach to conventional LNA circuit design strategies in order to achieve natural electronic protection, without a limiter placed before the LNA#A or LNA#R or without turning-off the DC-biasing: this protection option benefits from maintaining the LNA in an operational detection situation for longer when the incident input signal increases, without any degradation in electrical performance (DC and RF) or noise (NF50), even after many sequences of RF step stress.

Study on transient photocurrent induced by energy level defect of schottky diode irradiated by high power pulsed laser

The transient photocurrent is one of the key parameters of the spatial radiation effect of photoelectric devices, and the energy level defect affects the transient photocurrent. In this paper, by studying the deep level transient spectrum of a self-designed Schottky diode, the defect properties of the interface region of the anode metal AlCu and Si caused by high-temperature annealing at 150 ℃, 200 ℃ and 300 ℃ for 1200 h have been quantitatively analyzed. The study shows that the defect is located at the position of + 0.41 eV on the valence band, the concentration is 2.8 times 1013/cm2, and the capture cross section is sigma = 8.5 times 1017. The impurity energy level mainly comes from the diffusion of Al atom in anode metal. We found that the defect did not cause the electrical performance degradation and obvious morphology change of the device, but the transient photocurrent increased significantly. The reason is that the high temperature treatment results in a growth in the density of states at the interface between AlCu–Si. The more mismatched dislocations and recombination center increased the reverse current of the heterojunction. The above view is proved by the TCAD simulation test.

Failure Characterization of Silicone Rubber in Corrosive Environments Based on Leakage Current Characteristics

Due to the growing usage of composite insulators in transmission and distribution networks, the development of composite insulators has reached the stage of systematic reliability study. This paper discusses the failure properties of HTV silicone rubber in different energized corrosive environments and explores the characteristics that can characterize insulation failure. The findings demonstrate that the leakage current characteristics (the maximum values, the number of characteristic pulses, and cumulative charge) can effectively characterize the surface state of silicone rubber in corrosive environments. The flashover tests during the withstand voltage experiment accelerated the electrical performance degradation of silicone rubber and increased the leakage current. The three leakage current characteristics increase with experimental time, applied voltage, and fog conductivity. The occurrence of flashover is related to the fluctuation range of leakage current. The three leakage current characteristics in the alkali fog with the same conductivity and applied voltage are significantly higher than those in salt and acid fog. A failure characterization method of silicone rubber based on the proportion of pulse number and cumulative discharge is proposed in this paper. The findings are helpful in forecasting pollution flashovers and insulation failure in heavy fog, coastal, and industrial pollution areas.

Optically‐Boosted Planar IBC Solar Cells with Electrically‐Harmless Photonic Nanocoatings

AbstractAdvanced light management via front‐coated photonic nanostructures is a promising strategy to enhance photovoltaic (PV) efficiency through wave‐optical light‐trapping (LT) effects, avoiding the conventional texturing processes that induce the degradation of electrical performance due to increased carrier recombination. Titanium dioxide (TiO2) honeycomb arrays with different geometry are engineered through a highly‐scalable colloidal lithography method on flat crystalline silicon (c‐Si) wafers and tested on standard planar c‐Si interdigitated back‐contact solar cells (pIBCSCs). The photonic‐structured wafers achieve an optical photocurrent of 36.6 mA cm−2, mainly due to a broad anti‐reflection effect from the 693 nm thick nanostructured coatings. In contrast, the pIBCSC test devices reach 14% efficiency with 679 nm thick TiO2 nanostructures, corresponding to a ≈30% efficiency gain relative to uncoated pIBCSCs. In addition, several designed structures show unmatched angular acceptance enhancements in efficiency (up to 63% gain) and photocurrent density (up to 68% gain). The high‐performing (yet electrically harmless) LT scheme, here presented, entails an up‐and‐coming alternative to conventional texturing for c‐Si technological improvement that can be straightforwardly integrated into the established PV industry.

Quantitative Analysis of Channel Width Effects on Electrical Performance Degradation of Top-gate Self-aligned Coplanar IGZO Thin-film Transistors under Self-heating Stresses

In this study, a quantitative analysis was conducted on the effects of channel width on electrical performance degradation induced by self-heating stress (SHS) in top-gate self-aligned coplanar indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs). From the transfer and capacitance-voltage curves obtained before and after SHS, we revealed that the electrical performance of the TFT was nonuniformly degraded along the channel length direction and the degree of this degradation was more significant in TFTs with a wider channel width. The threshold voltage shift (ΔVSUBTH/SUB) under SHS in the fabricated IGZO TFT was mainly attributed to the increase in the density of shallow donor states and acceptor-like deep states in the IGZO active region and electron trapping into the fast and slow traps in the SiOSUBX/SUB gate dielectric. In addition, we conducted a decomposition of the SHS-induced ΔVSUBTH/SUB originated from each degradation mechanism using the subgap density of states-based ΔVSUBTH/SUB decomposition technique for TFTs with different channel widths. Although every ΔVSUBTH/SUB from each degradation mechanism increased as the channel width increased, increased electron trapping into the slow trap in the SiOSUBX/SUB gate dielectric was the dominant reason for the larger ΔVSUBTH/SUB under SHS in IGZO TFTs with a wider channel width.

Novel Trench Inner-Spacer Scheme to Eliminate Parasitic Bottom Transistors in Silicon Nanosheet FETs

A novel and feasible trench inner-spacer (TIS) scheme to eliminate undesired parasitic bottom transistors (trpbt) in gate-all-around (GAA) nanosheet (NS) field-effect transistors (FETs) is proposed based on fully calibrated Technology Computer-Aided Design (TCAD) simulation. Highly doped punch-through stopper (PTS) layers are generally used to suppress trpbt. Unfortunately, trpbt is still a fatal failure factor in electrical performance degradation when the source/drain (S/D) recess is overetched. Moreover, the proposed TIS scheme prevents the diffusion of S/D dopants toward the PTS region beneath the bottom gate, thereby inhibiting the formation of trpbt. Furthermore, the TIS-NSFETs exhibit excellent immunity to overetched S/D recess depth variations. Additionally, the thermal characteristics of the TIS scheme are compared to that of the bottom oxide (BOX) scheme forming dielectrics beneath the S/D epitaxies, one of the methods used to suppress trpbt. Lattice temperature caused by self-heating and thermal resistance in the TIS-NSFETs are much lower than that in the BOX-NSFETs for both n/p-type devices. The thermal advantage of TIS-NSFETs compared to BOX-NSFETs is confirmed in both DC and AC conditions, similar to an actual operating environment. Therefore, the proposed TIS scheme is highly recommended to eliminate the undesired trpbt without critical DC/AC degradation and to resolve poor heat dissipation problems in the BOX scheme simultaneously.

Highly Stable InSe-FET Biosensor for Ultra-Sensitive Detection of Breast Cancer Biomarker CA125.

Two-dimensional materials-based field-effect transistors (FETs) are promising biosensors because of their outstanding electrical properties, tunable band gap, high specific surface area, label-free detection, and potential miniaturization for portable diagnostic products. However, it is crucial for FET biosensors to have a high electrical performance and stability degradation in liquid environments for their practical application. Here, a high-performance InSe-FET biosensor is developed and demonstrated for the detection of the CA125 biomarker in clinical samples. The InSe-FET is integrated with a homemade microfluidic channel, exhibiting good electrical stability during the liquid channel process because of the passivation effect on the InSe channel. The InSe-FET biosensor is capable of the quantitative detection of the CA125 biomarker in breast cancer in the range of 0.01-1000 U/mL, with a detection time of 20 min. This work provides a universal detection tool for protein biomarker sensing. The detection results of the clinical samples demonstrate its promising application in early screenings of major diseases.

Degradation behaviors of silicone gel encapsulation material with moisture intrusion

In the applications of offshore wind turbines and high-speed trains, the power electronic devices suffer in harsh working conditions of high humidity. The moisture invades devices and induces failure of power modules. Therefore, it is necessary to investigate the degradation behaviors of encapsulation material with moisture intrusion. In this paper, the moisture absorption, chemical, and electrical properties of silicone gel under 85 °C&85%RH with long aging time is characterized. And the aging at 85 °C is chosen as a control. The influence of moisture absorption on the performance of silicone gel is discussed. The results showed that the wettest position locates at the mid-depth in silicone gels after desorption, which can be called as "depth effect" and is first discovered. Besides that, the mass loss during the aging is also observed and a comprehensive explanation considering the competition of absorption and dissolution is given here. Furthermore, a new phenomenon defined as "delayed degradation effect" is discovered. It is that the effect of moisture intrusion on electrical performance degradation in thin samples is delayed. In conclusion, moisture intrusion will degrade the electrical properties of silicone gel, so attention should be paid to power electronic devices working in high humidity conditions.

Simulation Aided Hardening of Power Diodes to Prevent Single Event Burnout

This article presents the coupled electrothermal simulation results of single event burnout (SEB) in power diode with field limiting rings termination structure. Two different hardening techniques of low carrier lifetime control and introducing the buffer layer are investigated comparatively in both the radiation tolerance improvement and the electrical performance degradation. Our simulations reveal that a significant reduction in the carrier lifetime is needed for the hardening of the power diode using only the carrier lifetime control method. However, the sharp increases in the forward voltage drop and the leakage current at the lower carrier lifetime make this hardening technique unacceptable. On the contrary, the addition of the buffer layer is able to improve the safe operating area under the heavy ion irradiation even up to the breakdown voltage, while the breakdown characteristics and the leakage current are kept unchanged and the increases in the forward voltage drop and the reverse recovery charge can be well controlled. In conclusion, adding a buffer layer is considered a superior and promising hardening technique.

P‐141: Student Poster: Modulation of Subthreshold Current in In‐Ga‐Zn‐O Thin‐film Transistor for OLED Display using Electrohydrodynamic Jet Printing

Here, we suggest simple method for multi value slope In‐Ga‐Zn O (IGZO) thin‐film transistors (TFTs) using electrohydrodynamic (EHD) jet printing. To induce multi value slope, parasitic channel was intentionally formed on top of IGZO main channel using EHD jet printing. By precisely controlling parasitic channel regime with EHD jet printing, multi value slope could be realized without degradation in electrical performance of original IGZO TFTs.