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Implantation-free mesa etched ultra-high-voltage 4H-SiC PiN diodes are fabricated, measured and analyzed by device simulation. The diode’s design allows a high breakdown voltage of about 19.3 kV according to simulations. No reverse breakdown is observed up to 13 kV with a very low leakage current of 0.1 μA. A forward voltage drop (VF) and differential on-resistance (Diff. Ron) of 9.1 V and 41.4 mΩ cm2 are measured at 100 A/cm2, respectively, indicating the effect of conductivity modulation.

For the first time, this work reports the fabrication of a p+-i-n + diode with a magnetic Mn-doped Ge quantum embedded in its intrinsic layer for photodetection and photovoltaic applications. The diode with Mn-doped Ge quantum dots is epitaxied by an ultra-high vacuum molecular beam epitaxy (UHV-MBE) reactor on a silicon substrate. Using atomic force microscopy and a superconducting quantum interference device to study the shape and magnetic properties of the Mn-doped Ge QDs revealed that they are uniform, dense, and ferromagnetic. The new p+-i-n + photodiode has a high rectification ratio of > 100 at a bias voltage of V b  = ± 1 V, a high breakdown voltage of 12 V, an ideality factor of n  = 1.86, a Schottky barrier height of ϕ B  = 0.72 eV, and a broad spectral response in the visible with a high photocurrent/dark ratio of about 100. These original results pave the way for the real integration of magnetic Mn-doped Ge quantum dots in advanced optoelectronic and spintronic devices.

We present a novel X-band 1-bit reconfigurable transmitarray with excellent polarization conversion. The basic element consists of two layers of metal patterns connected by a metal through-hole and feed structures. The top layer is used to realize a 1-bit phase response by controlling the states of two PIN diodes; the bottom layer is composed of a rectangular patch with a U-slot to realize conversion from linear polarization to cross polarization. The agreement between simulation and measurement results indicates that when the diode states are switched in turn, this unit achieves the phase difference of cross-polarized transmitted waves within 180° ± 15° and high transmittance in a broad band. The scattering patterns demonstrate that beam splitting or multi-beam generation can be achieved by controlling the different coding sequences of each column unit. The element offers low transmission loss, wide bandwidth of 1-bit phase control, and small thickness for easy integration. Thereby, it has numerous potential applications in radar and wireless communications.

In this work, we present a demonstration of a high-aspect ratio, three-dimensionally structured betavoltaic device. High-aspect ratio silicon PIN diodes were used as the semiconductor absorber and 147 PmCl 3 was used as the beta emitter. Three devices were fabricated with 147 Pm activities of 2.4 mCi, 7.4 mCi, and 29.5 mCi. The device with the highest activity produced an initial power output of 200 nW and was monitored over a period of 8 months to observe the current–voltage behavior over time, during which time the output current decreased in accordance with the radioactive half-life of 147 Pm. Small deviations in the output current of a few percent during the long-term measurement were found to be attributable to the humidity in the room where the experiment was done. The output current generated from the devices was 68–77% of the theoretical maximum, indicating significant infiltration of the radioisotope into the ridged structures.

This paper presented a new circular polarization reconfigurable antenna for 5G wireless communications. The antenna, containing a semicircular slot, was compact in size and had a good axial ratio and frequency response. Two PIN diode switches controlled the reconfiguration for both the right-hand and left-hand circular polarization. Reconfigurable orthogonal polarizations were achieved by changing the states of the two PIN diode switches, and the reflection coefficient |S11| was maintained, which is a strong benefit of this design. The proposed polarization-reconfigurable antenna was modeled using the Computer Simulation Technology (CST) software. It had a 3.4 GHz resonance frequency in both states of reconfiguration, with a good axial ratio below 1.8 dB, and good gain of 4.8 dBic for both modes of operation. The proposed microstrip antenna was fabricated on an FR-4 substrate with a loss tangent of 0.02, and relative dielectric constant of 4.3. The radiating layer had a maximum size of 18.3 × 18.3 mm2, with 50 Ω coaxial probe feeding.

This work presents a multiband, frequency-reconfigurable antenna developed for cognitive radio systems. Cognitive radio is an advanced wireless communication framework capable of autonomously sensing vacant spectrum bands and reconfiguring its transmission parameters to enhance spectral efficiency and mitigate interference. The proposed antenna is implemented using a rectangular microstrip patch structure with Rogers RT5880 substrate material with overall dimensions of 45 × 45 × 1.5 mm 3 . Reconfigurability is facilitated by three PIN diodes integrated between the radiating sections, enabling discrete switching among multiple frequency modes. The antenna successfully covers several operational bands, including 1.9 GHz (4G LTE), 2.45 GHz (Wi-Fi), 5.4 GHz (WLAN), and 5.9 GHz for dedicated short-range communication (DSRC). Across all bands, the voltage standing wave ratio (VSWR) remains below 1.5, indicating excellent impedance matching. The design achieves an efficiency of 89% and a maximum gain of 3.5 dBi. A prototype of the antenna was fabricated and experimentally characterized, and the measured results exhibit close agreement with the simulation data, thereby confirming the reliability and practical viability of the proposed design.

In this paper, we propose a reconfigurable metasurface antenna for beam switching applications. The reconfigurable metasurface is formed by uniformly distributed double-split square rings loaded with positive-intrinsic-negative (PIN) diodes for dual operations of a wave reflector and a wave director. Specifically, when the PIN diodes are forward biased, an epsilon-negative (ENG) metasurface is realized which reflects all incident waves with appropriate polarization; when the diodes are reverse biased, at the same operating frequency, a mu-near-zero (MNZ) metasurface is acquired which directs wave propagation. For excitation, a dipole radiator loaded with the same type of PIN diode is designed. Simulation and measurement results show good agreement and verify the beam switching functionality of the proposed metasurface antenna.

Application of highly N-doped buffer layers or a (N+B)-doped buffer layer to PiN diodes to suppress the expansion of Shockley stacking faults (SSFs) from the epilayer/substrate interface was studied. These buffer layers showed very short minority carrier lifetimes of 30-200 ns at 250°C. The PiN diodes were fabricated with buffer layers of various thicknesses and were then tested under high current injection conditions of 600A/cm 2 . The thicker buffer layers with shorter minority carrier lifetimes demonstrated the suppression of SSFs expansion and thus that of diode degradation.

In this article a compact frequency reconfigurable antenna is presented for wireless communication applications of industrial, scientific and medical band (ISM). The proposed antenna model is designed with the dimensions of 58mm×48 mm on FR4 epoxy of dielectric constant 4.4 with the thickness of 0.8 mm. The proposed antenna consists of defected T-shape ground plane, which acts as a reflector. In the design of frequency reconfigurable antenna, BAR 64-02V PIN diodes are used as switching elements and antenna is fed by microstrip transmission line. The proposed antenna can switch at different frequencies (2.5 GHz, 2.3 GHz and 2.2 GHz) depending on the biasing voltage applied to the PIN diodes. The current antenna showing VSWR < 2 in the operating band and providing peak realized gain of 3.2 dBi. A good matching obtained between expected and the measured results.

This research article represents the design of a simple, smaller, and novel frequency reconfigurable patch antenna for 5G communication using PIN diodes. This antenna operates in both mid-5G and high-5G bands. The antenna is intended to operate in eight distinct modes with three PIN diodes in 5G wireless communication covering 27.46–50 GHz of high-5G band (range n257/n258/n260/n261/n262) and frequencies of the 3–6 GHz of mid-5G band (range n77/n78/n79/n46). The antenna has an overall size of 20 mm × 25 mm × 1.6 mm and is placed upon a low-cost FR4 substrate. A higher radiation efficiency from 75% to 98% is achieved in all the different modes. The resonant frequencies are around 3.46, 4.43, 5.83, 31.8, 35.5, and 46 GHz in different modes of operation. Different switching statuses have been carried out in this research work and their performances have also been illustrated in the form of surface current distribution in different resonant frequencies. The simulated and measured results are compared to highlight its proposed design operation.