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关键词： MOSFET   Gallium   Silicon carbide   Semiconductor device modeling   Logic gates   Semiconductor process modeling   Silicon   Nitrogen   Ion implantation   High-voltage techniques   Beta-phase gallium oxide (beta-Ga2O3) MOSFET   current blocking layer (CBL)   medium-voltage device   nitrogen ion implantation   power loss   temperature dependence  

摘要： The structural design, static, dynamic power losses and short-circuit (SC) robustness of vertical Ga2O3 planar gate mosfets for medium voltage (3300-6500 V) ratings are first analyzed and comparatively investigated by technology computer-aided (TCAD) simulation. The specific on-resistance of Ga2O3 planar mosfets is 5.85 m Omegacm(2) (3300 V), 14.3 m Omegacm(2) (4500 V) and 30 m Omegacm(2) (6500 V). The Baliga figure of merit of 3300 V rated Ga2O3 mosfets is up to 2.53 GW/cm(2) (R-on,R-sp = 5.85 m Omegacm(2), BV = 3840 V, E-max(gate oxide)<4.5 MV/cm). In the third quadrant, Ga2O3 planar mosfets have a higher turn-on voltage (|V-on| > 5 V) than SiC mosfets, but lower on-resistance (7.5 m Omegacm(2)). Moreover, the switching power loss of 3300 V 1000 m Omega Ga2O3 planar mosfets is almost same as that of SiC mosfets. The reverse recovery time and reverse recovery charge of the channel diode are 8.5 ns and 18 nC, respectively. Overall, Ga2O3 planar mosfets have lower conduction losses and promising switching losses. However, its SC robustness is weaker than that of SiC. The main reason for this is the low thermal conductivity and lattice heat capacity. These findings provide meaningful references for vertical Ga2O3 planar gate mosfet deployment in future application scenarios.

关键词： Bandpass filters  

摘要： In this paper, a compact defected ground structure loaded ultra high frequency dual-band bandpass filter is designed and implemented based on multilayer liquid crystal polymer technology. This novel filter is simply composed with several lumped and semi-lumped elements, to create a dual-passband response. In order to enhance the out-of-band rejection, a feedback capacitor Cz at the in/out ports of the filter is introduced, and four transmission zeros (TZs) are obtained outside the pass band. Furthermore, the position of TZs can be determined by adjusting the value of Cz. The schematic and design process of the filter are given in this paper. The center frequencies of dual-band bandpass filter are 0.9 GHz and 2.45 GHz, and the 3-dB bandwidths are 13.7% and 14.3%, respectively. The circuit size is 11mm × 9.5 mm × 0.193 mm. The proposed filter has been fabricated and tested, and the measured result is in good agreement with the simulation result. © Shanghai Jiao Tong University 2023.

关键词： thermoelectric   PVDF   carbon nanotube   tape casting   ferroelectric   polarization  

摘要： Flexible thermoelectric (TE) films and devices have potential applications in wearable technology and the Internet of Things. One of the main challenges is how to simultaneously achieve good TE performance and high chemical/thermal stability in air with low cost and large-scale production. To address this, we utilized tape casting to fabricate composite films of polyvinylidene fluoride (PVDF) and multi-walled carbon nanotubes (MWCNTs). In the composite, polar beta-PVDF introduced by hot pressing can decouple the electrical conductivity and Seebeck coefficient and significantly lead to enhanced power factor of MWCNTs/PVDF composite film. As a result, the MWCNTs (60 wt%)/PVDF film has a power factor of 1.1-1.4 mu W m-1 K-2 near room temperature. The film also has excellent flexibility and stability in the air. Its power factor is decreased by only 9% after 1000 bends and can keep stable in air for above 6 months, which is much longer than that (15 days) of Bi2Te3/PEDOT: PSS film. A demo TE device with 10 p-type legs has an output voltage of 11.5 mV and output power of 47.53 nW at a temperature difference of 60 degrees C. The above descriptions make the MWCNTs/PVDF films have a significant advantage in the commercial application of flexible TE devices. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)/(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(PVDF)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(MWCNT)(sic)(sic)(sic)(sic)(sic). (sic) (sic)(sic)(sic)(sic)(sic)PVDF(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic), (sic)(sic)(sic)(sic)MWCNT

关键词： Metals   Logic gates   MOSFET   Fabrication   Transistors   Gold   Transmission electron microscopy   Surface treatment   Performance evaluation   Silicon   Lift-off   molybdenum disulfide (MoS2)   photolithography   photoresist (PR) trimming   transition-metal dichalcogenide (TMD)  

摘要： novel approach for fabricating molybdenum disulfide (MoS2) transistors with sub-100-nm gate length is reported. Unlike the traditional lift-off process, the photoresist (PR) is not in contact with the MoS2 channel, while the metal deposited in the source/drain (S/D) areas is not bridged with that on PR through the PR sidewalls. A sacrificial oxide layer between the channel and the PR enables the two distinct features, which are done after generating the PR pattern that defines the S/D regions, selectively removing the sacrificial oxide to suspend the PR between the source and drain regions. When metal is subsequently deposited, the metal on the PR will naturally disconnect from that in the S/D regions due to the air gap between the PR and the channel. The new metal-bridging-free process frees the fabricated devices from many issues encountered in the traditional lift-off process. Besides, we combined the I-line photolithography and a novel PR trimming technique to demonstrate the feasibility of this approach in fabricating nanometer-scaled devices with high throughput. The fabricated MoS2 transistors with Au contacts exhibit S/D series resistance of 2.4 k Omega-mu m.

关键词： Voltage measurement   Semiconductor device measurement   Temperature measurement   MOSFET   Inverters   Bridge circuits   Semiconductor diodes   Current measurement   Monitoring   Silicon carbide   Condition monitoring (CM)   converter-level   converter-level  

摘要： Condition monitoring technology can significantly improve system reliability by monitoring the device degradation process in real-time and implementing predictive maintenance. on-state voltage is the most practical health monitoring indicator for SiC mosfets so far, and their online extraction technology is a challenge for current research. Existing converter-level on-state voltage measurement circuits cannot well maintain low error within a wide temperature range and cannot individually measure the on-state voltage of each semiconductor. To address these limitations, this article proposes a wide temperature range and high-accuracy converter-level on-state voltage measurement method with localization function for SiC mosfets. First, the operating principle and individually measured function of the proposed method in a single-phase inverter are illustrated. Then, the steady-state error & varepsilon;(t) and response time T of the proposed circuit are analyzed theoretically to prove the feasibility of the method. It is proved that the & varepsilon;(t) is independent of the input on-state voltage. Finally, a detailed comparison was made with existing circuits in terms of circuit performance and a prototype is built to prove the ability of the proposed method to individually measure each semiconductor. The circuit is verified to have higher accuracy (approximate to 0.01%) over a wider temperature range (25 degrees C-100 degrees C) and fast dynamic response (approximate to 450 ns).

关键词： Channel surface potential   Charge control model   Intrinsic channel   Lambert W function   MOSFET compact model   Undoped body   Wright omega function  

摘要： The unwanted low-level doping present in supposedly undoped MOSFET channels has a significant effect on charge control and Lambert W function-based inversion charge MOSFET models, as well as on subsequent drain current models. We show that the hypothetical intrinsic MOSFET channel approximation, often used to describe a nominally undoped channel, produces significant errors, even for the low-level concentrations resulting from unintentional doping. We show that the traditional charge control model, which mathematically describes the gate voltage as the sum of one linear and one logarithmic term of the inversion charge, is only valid for the hypothetically intrinsic case. However, it may still be used for nominally undoped but unintentionally low-doped channel devices within the region of operation where the majority carriers are the dominant charge. With this in mind, we present here a better approximation of the nominally undoped MOSFET channel surface potential. We also propose an improved modified expression that describes the gate voltage as the sum of one linear and two logarithmic terms of the inversion charge. A new approximate drain current control formulation is also proposed to account for parasitic series resistance and/or mobility degradation. The new model agrees reasonably well with measurement data from nominally undoped vertically stacked GAA Si Nano Sheet MOSFETs.

关键词： Power device   P-MOSFET   Total ionizing dose effect   Finite element method   Numerical analysis  

摘要： In this study, the degradation of electrical and thermal properties of a packaged power semiconductor device due to cumulative radiation dose was numerically evaluated using electrical-thermal simulations. Si P-channel MOSFET devices were irradiated stepwise using a cobalt-60 gamma source. The changes in the electrical performance of the irradiated devices and the changes in the thermal conductivity of the encapsulation were identified. In addition, the changes in the thermal and electric properties of equivalent chips with changes in drain current and encapsulation surface temperature were numerically analyzed using electric-thermal multiphysics analysis. The results revealed that with the cumulative radiation dose rising from zero to 3000 krad, the chip's equivalent resistance increased significantly by 442.66 %, from 1.301 to 7.06 Omega center dot mm. Concurrently, thermal conductivity decreased by 88.53 %, from 24.27 to 2.96 W/m center dot K, and thermal resistance increased by 391 %, from 4.14 degrees C/W to 20.33 degrees C/W. These results quantitatively establish the degradation of electrical and thermal behavior of packaged P-channel Si MOSFETs due to radiation, as calculated by finite element analysis.

关键词： Wire   Monitoring   Silicon carbide   MOSFET   Voltage   Logic gates   Degradation   Junctions   Kelvin   Temperature sensors   reliability   multichip SiC MOSFET modules   bond wire lift-off   unevenness  

摘要： Monitoring bond wire lift-off unevenness is the basis for high-reliability operation of multichip silicon carbide (SiC) metal oxide semiconductor field effect transistor (mosfet) power modules. The traditional methods of monitoring bond wire lift-off can only monitor the overall number of the bond wire lift-off for one module. In this article, a new method is proposed to monitor the number of the bond wire lift-off for each parallel chip, which breaks through the limitations of traditional methods. A Kelvin source electrode is added in each parallel chip of the module. Under a constant current source, the voltage ratio related to the bond wires is used to monitor the number of bond wire lift-off for the chip. The validity of the proposed method is verified online by experiments based on a buck converter, a half-bridge inverter, and a double pulse test. Experiments show that the number of bond wire lift-off of each chip can be effectively monitored by the voltage ratio. The normal operation of the converter is not disturbed by the proposed method. The proposed method is not affected by the junction temperature and the gate-oxide degradation of SiC mosfet.

关键词： Demodulation   Noise   Isolators   Delays   Pulse width modulation   Gate drivers   MOSFET   Short-circuit currents   Propagation delay   Inverters   Demodulator   gate driver IC   low power consumption   signal isolator   silicon carbide (SiC)   wide bandgap (WBG) power semiconductor  

摘要： Wide-bandgap (WBG) devices, such as silicon carbide and gallium nitride, offer higher switching frequencies and power density compared to traditional silicon insulated gate bipolar transistors, making them suited for high-voltage and high-power-density applications. However, in systems with multiple WBG devices, large variations in source voltages of each gate driver circuit not only necessitate signal isolators to indirectly transmit control signals but also require effective modulation and demodulation techniques to ensure the reliability of signal transmission. Therefore, this letter proposes a low-power demodulator circuit that reduces both malfunctions from external noise during demodulation and the propagation delay difference between rising and falling edges. By utilizing leakage currents and employing thyristor structures, the circuit achieves an average current consumption under 37 mu A at a 100-MHz input modulated signal, representing a 43% reduction compared to conventional structures. In addition, it suppresses the difference in propagation delay between rising and falling edges to below 3.5%, even when the operating temperature varies from 0 degrees C to 100 degrees C. The proposed circuit was fabricated in the 180-nm bipolar-CMOS-DMOS (BCDMOS) process, and the chip area is 1584 mu m(2).

关键词： Retroreflectors   Eavesdropping   Wires   MOSFET   RF signals   Headphones   Voltage   Semiconductor device modeling   Radio frequency   Nonlinear distortion   Audio eavesdropping   radio-frequency retroreflector attack (RFRA)   EM side-channel attack  

摘要： Recent studies have demonstrated the feasibility of eavesdropping on audio via radio frequency signals or videos, which capture physical surface vibrations from surrounding objects. However, these methods are inadequate for intercepting internally transmitted audio through wired media. In this work, we introduce radio-frequency retroreflector attack (RFRA) and bridge this gap by proposing an RFRA-based eavesdropping system, RF-PARROT(2), capable of wirelessly capturing audio signals transmitted through earphone wires. Our system entails embedding a tiny field-effect transistor within the wire to establish a battery-free retroreflector, whose reflective efficiency is correlated with the amplitude of the audio signal. To preserve the details of audio signals, we designed a unique retroreflector using a depletion-mode MOSFET (D-MOSFET). This MOSFET can be triggered by any voltage level present in the audio signals, thus guaranteeing no information loss during activation. However, the D-MOSFET introduces a nonlinear convolution operation on the original audio, resulting in distorted audio eavesdropping. Thus, we devised an engineering solution which utilized a novel convolutional neural network in conjunction with an efficient Parallel WaveGAN vocoder to reconstruct the original audio. Our comprehensive experiments demonstrate a strong similarity between the reconstructed audio and the original, achieving an impressive 95% accuracy in speech command recognition.