Photoconductive Semiconductor Switches Research Articles

High Current Density Diamond Photoconductive Semiconductor Switches With a Buried, Metallic Conductive Channel

High Current Density Diamond Photoconductive Semiconductor Switches With a Buried, Metallic Conductive Channel

Effects of spot size on the operation mode of GaAs photoconductive semiconductor switch employing extrinsic photoconductivity

To guide the illuminating design to improve the on-state performances of gallium arsenide (GaAs) photoconductive semiconductor switch (PCSS), the effect of spot size on the operation mode of GaAs PCSS based on a semi-insulating wafer with a thickness of 1 mm, triggered by a 1064-nm extrinsic laser beam with the rectangular spot, has been investigated experimentally. It is found that the variation of the spot size in length and width can act on the different parts of the output waveform integrating the characteristics of the linear and nonlinear modes, and then significantly boosts the PCSS toward different operation modes. On this basis, a two-channel model containing the active and passive parts is introduced to interpret the relevant influencing mechanisms. Results indicate that the increased spot length can peak the amplitude of static domains in the active part to enhance the development of the nonlinear switching, while the extended spot width can change the distribution of photogenerated carriers on both parts to facilitate the linear switching and weaken the nonlinear switching, which have been proved by comparing the domain evolutions under different spot sizes.

Influence of Pinch Effect on the Lifetime of a 2MW Silicon Carbide Photoconductive Semiconductor Switch

Influence of Pinch Effect on the Lifetime of a 2MW Silicon Carbide Photoconductive Semiconductor Switch

Capacitance Dependence of Carrier Transport in Nonlinear GaAs Photoconductive Semiconductor Switch at nJ Optical Excitation

Capacitance Dependence of Carrier Transport in Nonlinear GaAs Photoconductive Semiconductor Switch at nJ Optical Excitation

Low ON-Resistance and High Peak Voltage Transmission Efficiency Based on High-Purity 4H-SiC Photoconductive Semiconductor Switch

Low ON-Resistance and High Peak Voltage Transmission Efficiency Based on High-Purity 4H-SiC Photoconductive Semiconductor Switch

Influence of optical grating on the triggering efficiency of VCSI silicon carbide photoconductive semiconductor switch

In this article, we present a new configuration of opposed-contact vanadium-compensation semi-insulating (VCSI) 4H–SiC photoconductive semiconductor switch (PCSS) to reduce the input laser energy for operation. The configuration is made up of three parts: the PCSS with optical grating, the convex lens in front of PCSS, and the additional reflector behind PCSS. Periodic surface structures were fabricated on the VCSI 4H–SiC substrate by ultrafine femtosecond laser direct writing to etch optical gratings. The microstructure on the lower surface plays the role of reflection grating, so that the laser forms a specific distribution pattern and enhances the laser absorption. Experiments and simulations show that the triggering efficiency increased 3.7 times compared to PCSS without grating at 532 nm laser. And output voltage can reach 90 % of the input bias voltage. This SiC PCSS optical system significantly reduces the laser energy without reducing the electrodes spacing.

Comparison of photoconductive semiconductor switch parameters with selected switch devices in power systems

Comparison of photoconductive semiconductor switch parameters with selected switch devices in power systems

Reducing Dark-State Current for GaAs Photoconductive Semiconductor Switch by Ultrafine Grinding Process

Reducing Dark-State Current for GaAs Photoconductive Semiconductor Switch by Ultrafine Grinding Process

Switching jitter of avalanche gallium arsenide photoconductive semiconductor switch influenced by multiple avalanche domains.

The stability of synchronous operation is directly related to the time jitter of the gallium arsenide photoconductive semiconductor switch (GaAs PCSS). In this work, a numerical model for the switching jitter of avalanche GaAs PCSS is established, and the impacts of triggering optical energy and bias electric field on the switching jitter are investigated numerically based on an equivalent bulk current channel. The proposed numerical model predicts well the changing characteristics of switching time as well as switching jitter, which has been demonstrated by the experimental results. On this basis, the theory of multiple avalanche domains is introduced to compare the domain evolutions influenced by the bias electric field and triggering optical energy. The results indicate that the reduction of switching jitter is significantly determined by the accelerated formation and evolution of avalanche domains, which provides a good explanation of the jitter mechanism of switching time.

Design of a lateral photoconductive semiconductor switch with a low resistivity region on semi-insulating GaN to enhance breakdown characteristics

The breakdown characteristics of the semi-insulating lateral GaN photoconductive semiconductor switches (PCSS) with low resistivity region (LRR) structure were simulated. The design, which can reduce the peak electric field by adjusting the electric field distribution for PCSS, was first proposed. In comparison to conventional field plate and n-type doping below the electrode structures, the LRR structure robustly enhances the breakdown characteristics of PCSS while reducing the influence of on-state characteristics. The impact of different structural parameters on the breakdown voltage and on-state characteristics was investigated. In the case of a small size device with a 5 μm electrode gap, the LRR structure is able to decrease the peak electric field by 54 % at 400 kV/cm and increase breakdown voltage by 45 %. When the electrode gap is increased to 0.25 mm, under a bias voltage of 5 kV, the field plate structure can reduce the peak electric field by 35 %, but the LRR structure can reduce the peak electric field by 42 %. When applied a voltage of 2 kV, the PCSS with the LRR structure triggered by a laser pulse with a wavelength of 532 nm and an energy of 265 μJ has a minimum on-resistivity being less than 0.5 Ω cm and the resistivity ratio between the off and on states reaching up to 1 × 108.

Computational Modeling and Measurement of a Waveguide Chamber for Two Photoconductive Semiconductor Switches

Computational Modeling and Measurement of a Waveguide Chamber for Two Photoconductive Semiconductor Switches

The Critical State of GaAs Photoconductive Semiconductor Switch in a Capacitive Storage Loop

The Critical State of GaAs Photoconductive Semiconductor Switch in a Capacitive Storage Loop

Investigating the Properties of a New Lateral 4H-SiC Photoconductive Semiconductor Switch With a Stacked Structure

Investigating the Properties of a New Lateral 4H-SiC Photoconductive Semiconductor Switch With a Stacked Structure

Analysis of the Avalanche Operation of a GaN Photoconductive Semiconductor Switch

Analysis of the Avalanche Operation of a GaN Photoconductive Semiconductor Switch

A photo-controlled, all-solid, and frequency-tunable ultra-wideband pulse generator.

With the continuous exploration of the bioelectric effect, nanosecond and picosecond pulsed electric fields used in cancer therapy and drug introduction have attracted great attention. In this paper, an ultrashort pulsed electric field generator is proposed, which connects two photoconductive semiconductor switches in parallel to generate unipolar and bipolar pulses. We described the experimental scheme of the generator and the simulation of the radio frequency combiner. A 532nm laser with pulse widths of 1ns and 500ps is used to trigger the photoconductive semiconductor switches. The experimental results show that the scheme can achieve adjustments of 357 and 720MHz for the center frequency and the 3 dB bandwidth, respectively. The results confirm that this proposed scheme can be used for unipolar/bipolar frequency-adjustable ultra-wideband pulse generation.

Effect of proton irradiation induced localized defect clusters on recovery time and leakage current in silicon photoconductive semiconductor switches

Pulse recovery time in semiconducting devices depends strongly on minority carrier lifetime, bandgap-type-dependent recombination, impurity concentration, and subband placement. In indirect bandgap solids, such as silicon, it is dominated by Shockley–Reed–Hall (SRH) recombination via trap-based recombination centers yielding slow recombination. The sluggish recombination then limits the pulse repetition rate and consequently the average power to a load. For decades, fabrication and irradiation techniques, such as Au- and Pt-diffusion, and energized electron-, proton-, and alpha particle-beam bombardment have been used to adjust minority carrier lifetime in silicon. These techniques generate shallow- and/or deep-level lattice defects to promote/retard trap-assisted SRH recombination. Despite investigating the characteristics of the generated defects on target material, the prior-art falls short in comprehensively addressing their effects on device-level architecture, specifically photoconductive switching devices. In this work, the effect of proton irradiation-induced localized crystal defect clusters on minority carrier lifetime in silicon photoconductive semiconductor switches is investigated when bombarded with 2.5–5 MeV beam energies with fluences between 9 × 1012–11 × 1013 cm−2 at room temperature. Photo-illuminated recovery characteristics for proton-beam (p-beam) irradiated device models with three distinct defect profiles have been studied using Silvaco TCAD and results have been compared with the electron-beam (e-beam) irradiation model with three different distinct defect profiles. At 30× lower defect density, recovery time trends in the p-beam irradiated device model were seen to be on the same order of magnitude as the e-beam irradiated model. At similar defect densities (1 × 1016 cm−3), the profile with a uniformly distributed bulk defect profile performed 10× better from a recovery time viewpoint compared with the e-beam irradiation. Furthermore, three orders of magnitude reduction in leakage currents were noticed in p-beam irradiated models.

Optimization design of electrode structure of GaAs photoconductive semiconductor switch

Previous studies revealed that changing the electrode structures of a gallium arsenide photoconductive semiconductor switch (GaAs PCSS) can significantly affect the local electric field and current density at the electrodes. Knowing the optimization of the electrode structures of GaAs PCSS can improve the withstand voltage performance and current carrying capability. In this work, we optimize the surface contact electrode structure of GaAs PCSS, and numerical simulations are performed to systematically study the electric field and current density distribution in the bulk of the device. The result shows that the maximum transverse current density and maximum longitudinal current density of the embedded 172° isosceles trapezoid electrode structure are smaller than other kinds of electrode structures, which is the most favorable for improving the withstand voltage and current carrying capability of GaAs PCSS.

A Method to Simulate Extrinsic Light Excitation of Vanadium-Compensated 6H-SiC

Extrinsic light excitation has much lower absorption coefficient compared to intrinsic light excitation, which can better utilize the “bulk” of semiconductor rather than a thin surface as the depth of light absorption is much larger, making it suitable for higher power applications. However, commercial technology computer aided design (TCAD) software has not developed a model for extrinsic light excitation. Therefore, we construct a model of Vanadium-compensated semi-insulating (VCSI) 6H-SiC photoconductive semiconductor switch (PCSS) illuminated with sub-bandgap light, and realize the process of light absorption at V deep acceptor level in Silvaco TCAD simulation by modifying the electron emission rate. Then, we simulate the transient response of 6H-SiC triggered by a nanosecond light pulse and discuss the feasibility of this method.

Modeling and Simulation of Fe-Doped GaN PCSS in High-Power Microwave

In this article, the characteristics of linear GaN photoconductive semiconductor switch (PCSS) in high-power microwaves are investigated by Silvaco TCAD (Technology Computer-Aided Design). By comparison of optical absorption efficiency among three types of PCSS structures, the optimized Fe-doped GaN PCSS is designed in a side-illuminated, vertical structure with a spot size of 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 8 mm. The photocurrent of side-illuminated GaN vertical PCSS (vPCSS) begins to saturate at 1.65 mJ with the increase of applied optical energy. The average saturated switch resistance and electron concentration of vPCSS under a bias voltage of 5–20 kV are almost 8.2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pmb\Omega $</tex-math> </inline-formula> and 3.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text{14}}$</tex-math> </inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-\text{3}}$</tex-math> </inline-formula> , respectively. As the device is in a saturated photocurrent state, the peak photocurrent is a linear function of bias voltage. As the device is in an unsaturated photocurrent state, improving the light energy is more effective than the withstand voltage of the device to increase photocurrent. Due to the short carrier lifetime, the GaN vPCSS has the response capacity to a 50-ps pulsewidth laser. Based on side-illuminated GaN vPCSS at the bias field 200 kV/cm, a narrowband microwave with adjustable frequency (3.3–5 GHz) could be generated. The maximum output power reaches up to 1.3 kW. Effects of anti-reflective (AR) and reflective coatings on optical absorption are investigated. The photocurrent of vPCSS with both AR and reflective coatings increases by 77.2% as compared with normal vPCSS.

High-Temperature Annealing of High Purity Semi-Insulating 4H-SiC and Its Effect on the Performance of a Photoconductive Semiconductor Switch

High-Temperature Annealing of High Purity Semi-Insulating 4H-SiC and Its Effect on the Performance of a Photoconductive Semiconductor Switch