Nanosecond square voltage pulse is of wide interest because of its potential military and industrial applications, such as high-power microwave (HPM). In this article, a gigawatt pulsed power generator (PPG) for HPM based on the multistage pulse forming networks (PFNs) with a voltage superposition using the Marx scheme, i.e., PFN-Marx generator, is proposed through the theory analysis, numerical simulation, processing manufacturing, and performance experiment. The PPG consists of the main subsystems of the primary power and pulse modulation subsystems. The primary power subsystem is a modular bipolar dc high-voltage generator based on the ac–dc–ac, high-frequency transformer, and voltage multipliers by using the power electronics switches. It can generate bipolar dc high voltage of $\pm$ 42 kV to charge the PFN-Marx generator. As for the pulse modulation subsystem, the PFN-Marx technique is preferred, which consists of 24-stage and six $\textit{L}$ - $\textit{C}$ sections. To verify the PPG, an experimental prototype is fabricated and tested. It has a characteristic impedance of about 40 $\boldsymbol\Omega$ and can deliver square voltage wave with an output voltage pulse of about 500 kV, full-width at half-maximum (FWHM) of 94 ns, and 10%–90% rise time of fewer than 35 ns, indicating its ability to deliver peak power beyond 6.25 GW. In addition, a transit-time oscillator was connected and can radiate microwave power of 0.8 GW at 12.89 GHz for the cathode voltage of 372 kV and the beam current of 9.3 kA.

This article proposes a scan driver circuit based on indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs) for multiple output signals. The proposed circuit could generate two overlapped output signals using a separate driving structure. The separate driving structure enabled the control nodes of each output signal to have a sufficiently high voltage during the output period. Consequently, the proposed circuit stably operated with the threshold voltage ( $\textit{V}_{\text{TH}}\text{)}$ varying from $-$ 3 to 4 V in the circuit simulation. The proposed scan driver circuit could reduce the circuit area because a single stage could output two output signals for two adjacent scan lines. Furthermore, the fabricated scan driver circuit exhibited a stable operation with multiple overlapped signals. Consequently, the proposed IGZO TFT-based scan driver circuit showed a stable circuit operation with multiple output signals through the separate driving structure.

In the present theoretical investigations, we have reported the potential of magnesium oxide nanoribbons (MgONRs) for spintronic applications by deploying density functional theory (DFT) in correlation with nonequilibrium Green’s function (NEGF). All the considered MgONRs are thermodynamically stable according to binding energy ( $\textit{E}_\textit{b}$ ) results. Pristine MgONR (HH-MgO-HH) is ferromagnetic (FM) metal while the selective edge hydrogenated MgONRs with one edge partially bare (HH-MgO-HB) and one edge partially hydrogenated (HB-MgO-BB) are half-metals in FM and anti-FM (AFM) ground states (GSs), respectively. Furthermore, the HH-MgO-HB and HB-MgO-BB are investigated for their transport characteristics. Current magnitude in HH-MgO-HB is negligibly small and hence HB-MgO-BB is further investigated for spintronic applications. Spin-based rectification characteristics are reported in AP spin orientation with a rectification ratio (RR) of the order of 10 $^\text{6}$ for spin-up currents. A very high spin filtering efficiency (SFE) is noticed in HB-MgO-BB with near 100% efficiency. Moreover, giant magnetoresistance (GMR) is noticed in HB-MgO-BB with computed value of 5.52 $\times$ 10 $^{\text{11}}$ and 1.00 $\times$ 10 $^{\text{10}}$ for spin-down and spin-up currents, respectively. Obtained findings suggest the MgONRs are promising candidates for future spintronics technology.

Vertical GaN-on-GaN Schottky barrier diode (SBD) fully grown by hydride vapor phase epitaxy (HVPE) was first demonstrated in this article. Due to the low-carbon impurity concentration grown by HVPE, the field effective mobility has been increased from 734 to 1188 cm $^{\text{2}}\cdot$ V $^{-\text{1}}\cdot$ s $^{-\text{1}}$ . The fabricated device with this technology shows a low turn-on voltage of 0.52 V and a high I $_{\biosc{on}}$ / I $_{\biosc{off}}$ ratio of 7.1 $\times$ 10 $^{\text{9}}$ . The specific ON resistance $\textit{R}_{\biosc{on}}$ was 1.69 m $\Omega \cdot$ cm $^{\text{2}}$ at the current density of 500 A/cm $^{\text{2}}$ . High breakdown voltage $\textit{V}_{\text{BR}}$ of 1370 V was achieved using He implantation technology. Among the reported vertical GaN SBDs with an indicated anode size, the highest figure of merit (FOM) ( $\textit{V}_{\text{BR}}^{\text{2}}/\textit{R}_{\biosc{on}}\text{)}$ of 1.1 GW/cm $^{\text{2}}$ has been achieved to date.

We investigated the power loss reduction of an n-channel 4H-silicon carbide (SiC) insulated-gate bipolar transistor (IGBT) with a blocking voltage of 10 kV by utilizing a box cell layout, which can enhance the conductivity modulation, instead of a conventional string cell layout. The box cell layout significantly reduced the on-voltage of SiC IGBTs, which are a 35% and 29% reduction in the specific differential on-resistance at 25 $^{\circ}$ C and 150 $^{\circ}$ C, respectively. Although enhancing the conductivity modulation should increase the turn-off loss, it has increased slightly, by 10% at 25 $^{\circ}$ C and by 5% at 150 $^{\circ}$ C with a load current of 250 A/cm $^{\text{2}}$ because the box cell layout can enhance the stored carrier, particularly near the emitter in the on-state. In contrast to the turn-off loss, turn-on loss was reduced by the box cell layout due to the enhancement of electron injection from the emitter, resulting in a lower total switching loss in comparison to a string-layout device. A lower on-voltage and switching loss of SiC IGBTs have both been achieved as a result of the box cell layout enhancing conductivity modulation enhancement.

N $_{\text{2}}$ O plasma treatment is widely implemented into the fabrication process of mass-produced amorphous oxide semiconductors for its effectiveness, simplicity, and cost efficiency. However, N $_{\text{2}}$ O plasma-treated amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) have been reported to exhibit reliability issues due to a nonideal threshold voltage ( $\textit{V}_{\text{th}}\text{)}$ shift that occurs under positive bias temperature stress (PBTS). Here, the cause of this abnormal positive bias temperature instability is investigated, and a simple solution applicable to the fabrication process for mass production is proposed. While the supply of N $_{\text{2}}$ O plasma in the fabrication chamber is immediately suspended after plasma treatment in mass production, the supply of N $_{\text{2}}$ O plasma in the chamber was maintained even during the postprocesses that follow plasma treatment for this study. While plasma-treated a-IGZO TFTs fabricated with the supply of N $_{\text{2}}$ O plasma turned off during the postprocesses exhibited nonideal negative $\textit{V}_{\text{th}}$ shifts under PBTS, the devices fabricated with N $_{\text{2}}$ O plasma supplied during the postprocesses exhibited superior electrical performance and reliability under bias stress. The defect and physical analyses demonstrate that the nonideal $\textit{V}_{\text{th}}$ shift is caused by leakage-current paths generated by the breakage of metal–oxygen bonds and the formation of weak bonds, such as $-$ OH bonds, that occur from plasma damage and bias temperature stress, respectively. This study demonstrates that maintaining the supply of N $_{\text{2}}$ O plasma during the postprocesses is a straightforward and effective method for ensuring robust a-IGZO TFTs in mass production.

For the first time, relative intensity noise (RIN) of an InAs-InP(113)B quantum dot (Q-Dot) laser is examined theoretically under the gain-switching condition with the application of a Gaussian pulse beam (GPB) to excited state (Exs) of the laser. The multi-population rate equations considering nonlinear gain are solved by the Runge–Kutta method. Noises are added to rate equations as Langevin noise sources and a different method is applied here for the addition of these noise sources to equations. In this method, new rate equations are defined to eliminate the cross-correlations between the noise sources to make them independent and simulate with independent white Gaussian random variables. Obtained results showed that RIN decreases with the increasing ac peak current and the increasing inhomogeneous broadening. It was also observed that further RIN reduction of about 30 dB/Hz and gain-switched short pulses with a high power due to Exs emission being obtained with the application of GPB to Exs of the laser. Moreover, it was demonstrated that while carrier noise generated from Exs and ground state (Grs) affect the RIN spectrum, there is no effect of wetting layer (Wly) carrier noise.