Photoconductive Semiconductor Switches Research Articles

Properties Investigation and Damage Analysis of GaN Photoconductive Semiconductor Switch Based on SiC Substrate.

The GaN photoconductive semiconductor switches (PCSSs) with low leakage current and large on-state current are suitable for several applications, including fast switching and high-power electromagnetic pulse equipment. This paper demonstrates a high-power GaN lateral PCSS device. An output peak current of 142.2 A is reached with an input voltage of 10.28 kV when the GaN lateral PCSS is intrinsically triggered. In addition, the method of retaining the AlGaN/GaN heterostructure between electrodes on PCSSs is proposed, which results in increasing the output peak current of the PCSS. The damage mechanism of the PCSS caused by a high electric field and high excitation laser energy is analyzed. The obtained results show that the high heat generated by the large current leads to the decomposition of GaN, and thus, the Ga forms a metal conductive path, resulting in the failure of the device.

Analysis of carrier dynamics and thermal effect of the GaAs photoconductive semiconductor switch in lock-on mode

Abstract The lock-on effect of the gallium arsenide photoconductive semiconductor switch (GaAs PCSS) at repetition rate aggravates the current crowding and electric field distortion, which significantly increases the risk of switch damage or even failure. Therefore, it is of great significance to investigate the carrier transport and the heat generation mechanism for improving the performance and longevity of GaAs PCSS in lock-on mode. The internal physical process of an opposed-electrode GaAs PCSS at low optical energy and strong electric field is analysed and discussed by experiment and simulation. A device-circuit hybrid simulation is employed to investigate the transient electric field, carrier concentration, and lattice temperature distribution within the GaAs PCSS in lock-on mode. The device temperature exhibits a positive correlation with the applied bias electric field, resulting in a peak temperature of 1037.25 K at an electric field of 38 kV/cm. The temperature distribution within the GaAs PCSS indicates a greater possibility for thermal breakdown and damage near the electrodes.

Enhanced Durability of High-Power Avalanche GaAs Photoconductive Semiconductor Switch Utilizing Advanced Double-Sided Cooling Configuration

Enhanced Durability of High-Power Avalanche GaAs Photoconductive Semiconductor Switch Utilizing Advanced Double-Sided Cooling Configuration

Physics-Based Artificial Neural Network Assisting in Extracting Transient Properties of Extrinsically Triggering Photoconductive Semiconductor Switches.

In this paper, a physics-based ANN assisting method for extracting transient properties of extrinsically triggering photoconductive semiconductor switches (ET-PCSSs) is proposed. It exploits the nonlinear mapping of ANN between transient current (input) and doping concentration (output). According to the basic laws of photoelectric device operating, two types of ANN models are constructed by gaussian and polynomial fitting. The mean absolute error (MAE) of forecasting transient photocurrent can be less than 10 A under low triggering optical powers, which verifies the feasibility of ANN assisting TCAD applied to PCSSs. The results are comparable to computation by Mixed-Mode simulation, yet even thousands of seconds of CPU runtime cost are saved in every period. To improve the robustness of the Poly-ANN predictor, Bayesian optimization (BO) is implemented for minimizing the curl deviation of photocurrent-time curves.

High-voltage AlGaN/GaN heterojunction lateral photoconductive semiconductor switch based on semi-insulating 4H-SiC substrate

A novel high-power AlGaN/GaN heterojunction lateral photoconductive semiconductor switch (PCSS) based on the SiC substrate is proposed, which achieves high dark-state resistance characteristics by groove etching. Under the action of biased electric field and incident laser, a high concentration of two-dimensional electron gas is formed at the heterojunction interface. The photo-generated free carriers transport along the heterojunction interface, which improves the utilization efficiency of photo-generated carriers. Moreover, the simulation of the current density distribution of the PCSS provides theoretical support for this phenomenon. Compared with the conventional GaN PCSS, the power capacity and conduction characteristics are further improved. The test results show that the output current of the device increases significantly after the introduction of the AlGaN/GaN heterojunction. At the biased voltage of ∼34 kV, the maximum output current of the AlGaN/GaN PCSS reaches 205 A.

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

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

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.