In this work, β-Ga₂O₃ thin films were grown on SiO₂ substrate by atomic layer deposition (ALD) and annealed in N₂ atmosphere to enhance the crystallization quality of the thin films, which were verified from X-rays diffraction (XRD). Based on the grown β-Ga₂O₃ thin films, vertical metal-semiconductor-metal (MSM) interdigital photodetectors (PDs) were fabricated and investigated. The PDs have an ultralow dark current of 1.92 pA, ultra-high photo-to-dark current ratio (PDCR) of 1.7×10⁶, and ultra-high detectivity of 4.25×10¹⁴ Jones at a bias voltage of 10 V under 254 nm deep ultraviolet (DUV). Compared with the horizontal MSM PDs under the same process, the PDCR and detectivity of the fabricated vertical PDs are increased by 1 000 times and 100 times, respectively. In addition, the vertical PDs possess a high responsivity of 34.24 A/W and an external quantμm efficiency of 1.67×10⁴%, and also exhibit robustness and repeatability, which indicate excellent performance. Then the effects of electrode size and external irradiation conditions on the performance of the vertical PDs continued to be investigated.

In this paper, a novel superjunction 4H-silicon carbide (4H-SiC) trench-gate insulated-gate bipolar transistor (IGBT) featuring an integrated clamping PN diode between the P-shield and emitter (TSD-IGBT) is designed and theoretically studied. The heavily doping superjunction layer contributes to a low specific on-resistance, excellent electric field distribution, and quasi-unipolar drift current. The anode of the clamping diode is in floating contact with the P-shield. In the on-state, the potential of the P-shield is raised to the turn-on voltage of the clamping diode, which prevents the hole extraction below the N-type carrier storage layer (NCSL). Additionally, during the turn-off transient, once the clamping diode is turned on, it also promotes an additional hole extraction path. Furthermore, the potential dropped at the semiconductor near the trench-gate oxide is effectively reduced in the off-state.

In this paper, a novel trench gate gallium nitride insulated gate bipolar transistor (GaN IGBT), in which the collector is divided into multiple regions to control the hole injection efficiency, is designed and theoretically studied. The incorporation of a P+/P- multi-region alternating structure in the collector region mitigates hole injection within the collector region. When the device is in forward conduction, the conductivity modulation effect results in a reduced storage of carriers in the drift region. As a result, the number of carriers requiring extraction during device turn-off is minimized, leading to faster turn-off speed. The results illustrate that the GaN IGBT with controlled hole injection efficiency (CEH GaN IGBT) exhibits markedly enhanced performance compared to conventional GaN IGBT, showing a remarkable 42.2% reduction in turn-off time and a notable 28.5% decrease in turn-off loss.

The method of terahertz (THz) resonance with a high-quality (high-Q) factor offers a vital physical mechanism for metasurface sensors and other high-Q factor applications. However, it is challenging to excite the resonance with a high-Q factor in metasurfaces with proper sensitivity as well as figure of merit (FOM) values. Here,  an all-dielectric metasurface composed of two asymmetrical rectangular blocks is suggested. Quartz and silicon are the materials applied for the substrate and cuboids respectively. The distinct resonance governed by bound states in the continuum (BIC) is excited by forming an asymmetric cluster by a novel hybrid method of cutting and moving the cuboids. The investigation focuses on analyzing the transmission spectra of the metasurface under different variations in structural parameters and the loss of silicon refractive index. When the proposed defective metasurface serves as a transmittance sensor, it shows a Q factor of 1.08×10⁴ and achieves a FOM up to 4.8×10⁶, which is obtained under the asymmetric parameter equalling 1 μm. Simultaneously, the proposed defective metasurface is sensitive to small changes in refractive index. When the thickness of the analyte is 180 μm, the sensitivity reaches a maximum value of 578 GHz / RIU. Hence, the proposed defective metasurface exhibits an extensive number of possible applications in the filters, biomedical diagnosis, security screening, and so on.

This article presents the design and performance of a single-pole double-throw (SPDT) switch operating in 50–110 GHz. The switch is fabricated in a 100-nm GaN high-electron-mobility transistors(HEMT) technology. To realize high-power capability, the dimensions of GaN HEMTs are selected by simulation verification. To enhance the isolation, an improved structure of shunt HEMT with two ground holes is employed. To extend the operation bandwidth, the SPDT switch with multi section resonant units is proposed and analyzed. To verify the SPDT switch design, a prototype operating in 50–110 GHz is fabricated. The measured results show that the fabricated SPDT switch monolithic microwave integrated circuit (MMIC) achieves an input 1 dB compression point (P_1dB) of 38 dBm at 94 GHz, and an isolation within the range of 33 dB to 54 dB in 50–110 GHz. The insertion loss of the switch is less than 2.1 dB, while the voltage standing wave ratios (VSWR) of the input port and output port are both less than 1.8 in the operation bandwidth. Based on the measured results, the presented SPDT switch MMIC demonstrates high power capability and high isolation compared with other reported millimeter-wave SPDT MMIC designs.