Three different insulator layers SiN_x, SiON, and SiO₂ were used as a gate dielectric and passivation layer in AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMT). The SiN_x, SiON, and SiO₂ were deposited by a plasma-enhanced chemical vapor deposition (PECVD) system. Great differences in the gate leakage current, breakdown voltage, interface traps, and current collapse were observed. The SiON MIS-HEMT exhibited the highest breakdown voltage and I_on/I_off ratio. The SiN_x MIS-HEMT performed well in current collapse but exhibited the highest gate leakage current density. The SiO₂ MIS-HEMT possessed the lowest gate leakage current density but suffered from the early breakdown of the metal–insulator–semiconductor (MIS) diode. As for interface traps, the SiN_x MIS-HEMT has the largest shallow trap density and the lowest deep trap density. The SiO₂ MIS-HEMT has the largest deep trap density. The factors causing current collapse were confirmed by Photoluminescence (PL) spectra. Based on the direct current (DC) characteristics, SiN_x and SiON both have advantages and disadvantages.

In this article, the degradation behavior of the electrical characteristics of AlGaN/GaN HEMTs subjected to radio frequency (RF) overdrive stress has been studied. Trap analysis based on low-frequency noise (LFN) and electroluminescence (EL) characterizations was carried out for AlGaN/GaN HEMTs before and after RF stress. The experimental results show that drain-to-source current of AlGaN/GaN HEMTs after RF stress is obviously lower than that of the fresh devices. The maximum change of drain-to-source current was up to 79 mA in the saturation zone. The threshold voltage drifted forward and gate-lag characteristic became worse for the AlGaN/GaN HEMTs after RF stress. The EL characterizations also showed the nonuniformity of channel illumination intensity, which indicates the distribution of electron of the channel nonuniform. Trap analysis was performed by using the LFN method, and the LFN results showed that the trap density increased by about one order of magnitude in the AlGaN/GaN HEMTs after RF stress, which would lead to more depletion of the channel two-dimensional electron gas (2DEG) electrons. The mechanism of increasing trap density could be attributed to defects induced by RF stress at AlGaN surface and AlGaN barrier layer. The experimental results may offer a useful reference in the design and application of RF of AlGaN/GaN HEMTs.

In this paper, we characterized and compared signal transmission performances of traces with different specifications of fiber weave. Measurements demonstrated that the dielectric constant, impedance fluctuation, and differential skew were all affected by fiber weave style. For flattened fiber weaves, the dielectric constant fluctuation reached 0.18, the impedance fluctuation amplitude was 1.0 Ω, and the differential skew was 2 ps/in. For conventional fiber weaves, the three parameters were 0.44, 2.5 Ω, and 4 ps/inch respectively. Flattened fiber weave was more favorable for high-speed signal control. We also discussed the other methods to improve the fiber weave effect. It turned out that NE-glass (new electronic glass) fiber weave also had better performance in reducing impedance fluctuation and differential skew. Furthermore, made the signal traces and fiber weave bundles with an angle or designing the long signal line parallel to the weft direction both are simple and effective methods to solve this problem.

High sensitivity, highly integrated, low-power consumption, and highly flexible pressure sensors are essential for applications in fields such as electronic skin, smart robotics, and human-AI interaction. In this study, a highly sensitive integrated pressure sensor was prepared on a flexible PI substrate which includes a thin-film transistors (TFTs)-based amplifier with a P(VDF-TrFE)/BaTiO₃ piezoelectric composite sensing unit. The sensing unit is connected to the extended gate of one In-doped ZnO (IZO) TFT, while the other IZO TFT serves as a load resistor for the amplifier. The integrated sensor can directly convert an external pressure applied to P(VDF-TrFE)/BaTiO₃ composite into a voltage (or current) signal and amplify it without an additional charge amplifier. The results indicate the integrated sensor exhibits a low power consumption of 100 ~ 200 μW, a high sensitivity of 0.64 V/kPa, and a rapid response time of 20 ms. The integrated sensor can be used to detect human movements and vital signs in real time, such as finger bending and stretching, pulse, and vocal cord vibrations, suggesting that the integrated sensor has a great deal of promise for application in wearable health monitoring systems.

Fe/Er multilayers were prepared by high-vacuum electron-beam evaporation system and their microstructures have been investigated. Henkel analysis was performed via isothermal remanent magnetization curve and direct current demagnetization curve. Magnetic measurement indicates that Fe/Er multilayers have an easy axis in film plane and a small value of positive magnetoresistance. It is showed that the Er layer will change to an amorphous structure when its thickness is below 3.5 nm. Hence, $\Delta m$ plots were established according to Henkel analysis data. The results show that $\Delta m$ plot has a strong dependence on the thickness of Fe and Er layers. When the thickness of Fe layer remained unchanged, $\Delta m$ plot indicated that the magnetic coupling was oscillating with the layer thickness; and when the thickness of Er layer was 8.8 nm, $\Delta m$ plot showed a positive-negative overturn of magnetic interaction, which revealed the interplay between the demagnetization and exchange coupling effect in multilayer. The explanation of $\Delta m$ plot was also discussed via a simplified model, i.e., a competition between demagnetizing interaction and magnetizing interaction.