Search

With unique characteristics, especially the simultaneous combination of high-power capacity and high repetition frequency, gallium arsenide photoconductive semiconductor switches (GaAs PCSS) have a wide range of applications in the field of pulsed power technology. In view of the ever-shrinking device area and the ever-increasing operating voltage of GaAs PCSS, its sidewall morphology has become more and more obvious on the lifetime and reliability of the device. To address this issue, this article comparatively investigates the influence of GaAs PCSS sidewall morphology on the electrical characteristics of the devices. The results show that the grinding process is favorable to improve the quality of the device sidewalls, so as to achieve the purpose of improving the life and reliability of the device. The leakage current of grinded-GaAs PCSS (G-GaAs PCSS) is reduced to $11.43~\mu \text{A}$ (average value) at a bias voltage of 45 kV, which is more than five times lower than that of the ungrinded-GaAs PCSS (U-GaAs PCSS). Notably, the G-GaAs PCSS enters the nonlinear mode with a lower threshold electric field and a high ${I}_{\text {light}}/{I}_{\text {dark}}$ ratio ( $1.45\times 10^{{7}}{)}$ . The microscopic morphology of the two devices was also experimentally analyzed, and the improvement in the electrical characteristics of the G-GaAs PCSS was attributed to the improvement of the sidewall quality of the device by the grinding process.

For 4H-SiC mosfets, the parasitic PiN body diode causes problems such as significant forward voltage drop of body diode and poor reverse recovery characteristics during high-temperature operation. A reasonable solution is a mosfet with an integrated Schottky barrier diode to deactivate the PiN body diode. Since SiC mosfets can operate at extremely high temperatures, the characterization of electrical parameters at high temperatures and changing with the temperature are very important for high power applications and system reliability. However, there is a lack of comparison and analysis of the two devices on electrical properties at ultrahigh temperatures. In this article, a 1.2 kV conventional mosfet and a mosfet integrated with a junction barrier Schottky diode (JBSFET) were fabricated with a consistent process flow. In the temperature range from 300 to 575 K, analytical models of the temperature-dependent electrical parameters of these two devices were established and compared, which were successfully verified by the measurements. These models can provide guidance for ultrahigh temperature applications of JBSFETs. Temperature-related expressions can also be used for junction temperature monitoring of temperature-sensitive electrical parameters. Experimental results show that JBSFET has better third quadrant conduction characteristics and higher temperature stability below 450 K, but loses obvious performance advantages at 575 K. So, the recommended operating temperature range of JBSFET is from 300 to 450 K. Finally, the continuous operation performance of the body diodes in buck converters is analyzed. The higher efficiency of buck converter based on JBSFET's body diode indicates its great application potential in compact converters, especially in the recommended temperature range.

AbstractThe irradiation effect of X-ray on the electrical properties of Schottky-barrier diode (SBD) and metal-semiconductor field-effect transistors (MESFET) based on the surface conductivity of hydrogen-terminated single-crystal diamond (SCD) epilayers was investigated. The Ohmic contact was formed by a Pd/Ti/Au multilayer and the Schottky metal was Al thin film for the fabrication of the diamond SBDs and MESFETs. The X-ray irradiation was performed with a dose of 100 kGy. It was observed that both the forward current of the SBDs and the drain current of the MESFETs experienced a reduction after the X-ray irradiation. The type of the single-crystal diamond substrate had an obvious effect on the radiation properties. For the MESFETs on the type-Ib SCD substrate, the variation of the drain currents as the irradiation was inhomogeneous across the devices. For the MESFETs on the type-IIa SCD substrate, the reduction of the drain currents is more uniform and the threshold voltage changed little upon X-ray irradiation. The partial oxidation in the air of the exposure area in the device and the edge of the Al gate may be responsible for the degradation of the device performance under X-ray irradiation. The passivation technique with radiation-robustness is needed for diamond devices based on the surface conductivity of diamond.

The activation of an Mg acceptor in p-GaN with rapid thermal annealing (RTA) assisted low-temperature supercritical fluid (SCF) treatment (RTA-A-SCF) was investigated. After RTA-A-SCF treatment, the luminescence band of the N vacancy in the PL spectra was significantly suppressed. An evident decrease in H concentration is also observed in secondary ion mass spectrometer measurements, it indicates an obvious decrease of Mg–H complexes in the p-GaN. In addition, the ohmic contacts have been well improved and the hole concentration has increased by an order of magnitude. The activation mechanism of RTA-A-SCF treatment was further analyzed by X-ray photoelectron spectroscopy.

The feed conversion rate (FCR) is a crucial economic trait in aquaculture fish, as feed costs account for the vast majority of aquaculture costs. Given the importance of this trait, there have little efforts to unravel the genomic architecture of FCR and identify key genes or genomic regions useful as selection makers. This situation may stem from the inherent swimming behavior of fish, which presents challenges in obtaining individual FCRs. In this work, we developed a specialized small cage culture system. Through this system, the Feed Conversion Ratio (FCR) of 300 individuals was successfully determined, marking the first successful determination of individual FCRs for turbot. The results revealed a range of FCR values from 35.3% to 192.6%, with an average of 126.5% ± 23.5%. On this basis, a genome-wide association study (GWAS) was conducted to identify single nucleotide polymorphisms (SNP) associated with FCR. A total of 2,613,115 SNPs on 22 chromosomes were selected for GWAS analysis by Efficient Mixed-Model Association eXpedited (EMMAX) software. A linear mixed model was employed to test the association between each SNP and FCR, considering population structure and genetic relatedness among individuals. Two significant SNPs on Chr6 were identified to be correlated with FCR. According to their localization in genome, four candidate genes were identified on Chr6, including uncharacterized protein KIAA1755, Kinesin Family Member 21B (KIF21B), Discs large homolog-associated protein 4B (DLGAP4B), and Copine 5B (CPNE5B), all of which are closely located in the genome and exhibit significant functional similarities. Our results will facilitate the implementation of marker-assisted selection in breeding programs and serve as a foundation for future research in this area.

Supercritical CO2fluid is reported as an effective media in optimizing the SiO2/SiC interface in 4H-SiC(0001) MOS structures at a temperature as low as 150 °C. After SCCO2treatment, the breakdown electric field is improved to 10.7 MV cm?1. The near-interfacial oxide traps is decreased from 1.62 × 1011to 1.84 × 1010cm?2. The interface state density at 0.2 eV below ECis reduced from 6 × 1012to 2.5 × 1012eV?1cm?2. A dynamic reaction model is proposed to explain the defect passivation reaction. This technique can be effectively applied to interface semiconductor devices to enhance performance.

Recent marked advances in diamond metal–oxide–semiconductor field‐effect transistors (MOSFETs) have raised the issue of gate reliability. Herein, the threshold voltage stability of MOSFETs based on hydrogen‐terminated diamond surface conductivity is examined. The electrical output characteristic curves are characterized by cyclic gate sweeping from reverse to forward gate bias (RF) and from forward to reverse gate bias (FR), respectively. The characteristics of drain current versus drain voltage are affected by the gate bias sweeping direction. Marked hysteresis is also observed in the transfer curves for the RF and FR gate sweeping. The different gate sweeping directions induce threshold voltage variation and hole mobility change. The facts that 1) no extra interface states are generated due to gate sweeping and 2) the trapped charge density depends on the gate oxide thickness, reveal that charge trapping occurs at the border of the gate oxide. The threshold voltage stability of metal–oxide–semiconductor field‐effect transistors (MOSFETs) based on hydrogen‐terminated diamond surface conductivity is examined. Marked hysteresis is observed in the transfer curves depending on the gate sweeping direction. The different gate sweeping directions induce threshold voltage variation and hole mobility change. It is revealed that charge trapping occurred at the border of the gate oxide.