Various operating modes of optically controlled multi-gate thyristors
Authors: WANG Lingyun , LIU Hongwei , YUAN Jianqiang , XIE Weiping , LUAN Chongbiao , LI Hongtao , ZHANG Jiande , CHEN Yi , HE Yang , LIU Xiaoli , GAO Bin ,   College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China,   Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, China,   Hubei TECH Semiconductors Co., Ltd, Xiangyang 441021, China,   Sichuan Research Center of Quality Safety and High Voltage Engineering Technology, Mianyang 621000, China
Published: January 2025

<sec>In order to meet the switching requirements of high-frequency pulsed-power systems and further enhance the peak power and turn-on speed of solid-state switches, comparative experiments on the structure of optically controlled multi-gate thyristors and the parameter of injected light are investigated in this work. The research results show that semiconductor chips based on the multi-gate thyristor structure exhibit different conduction characteristics under varying laser injection conditions, resulting in unique inflection point curves. By establishing a switching model and changing the injected light parameters and circuit parameter models, three conceptual operating modes for the optically controlled multi-gate thyristor are proposed, they being photonic linear mode (Mode A), field-induced nonlinear mode (Mode C), and hybrid amplification mode (Mode B).</sec><sec>Based on these concepts, the experimental validation tests are conducted, and the three distinct operating characteristics of the optically controlled multi-gate thyristor are confirmed. In Mode A, the conduction process is mainly related to the injected light power parameters, which is similar to the scenario in the linear mode of traditional light-guided switches, thus Mode A is suitable for the narrow pulse width applications. Mode C mainly focuses on carrier multiplication after injection, resembling the conduction characteristics of super thyristors (SGTO), and this mode is suitable for wide pulse width and high current applications. In Mode B, its initial conduction is related to the injected light parameters, while the later carrier multiplication continues from the earlier photonic linear mode, achieving characteristics of both fast rise time and wide pulse width, effectively integrating the advantages of light-guided switches and SGTOs.</sec><sec>In Mode A, when injected laser energy is 8.5 mJ, a pulse width is 10 ns, and peak power is 0.85 MW, the switch operates at a voltage of 5.2 kV, an output current of 8.1 kA, turn-on time (10%—90%) of 18.4 ns, with a d<i>i</i>/d<i>t</i> value reaching 440 kA/μs. The main characteristic is that the d<i>i</i>/d<i>t</i> of the switch is linearly related to the injected laser energy, thereby achieving a fast rise time output, which reflects the photonic linear conduction mode. This mode is suitable for high-power, narrow-pulse, and fast-rise-time applications, such as high-power microwave sources, and its characteristics are similar to those of gas switches.</sec><sec>In Mode C, when triggering laser energy is set to 250 μJ, a pulse width is 210 ns, and peak power is 1200 W, the switch operates at a voltage of 8.5 kV, a short-circuit current of 6 kA and a current rise time of 110 ns, achieving a d<i>i</i>/d<i>t</i> value exceeding 55 kA/μs. The key characteristic is that the d<i>i</i>/d<i>t</i> of the switch is unrelated to the injected laser energy but is related to the electric field applied across the switch, thus it can operates at large current and wide pulse width, which reflects the field-induced nonlinear conduction mode. This mode is suitable for high-power, wide-pulse, and slower-rise-time applications, such as large current detonation and electromagnetic drives, and its characteristics are similar to those of igniter tubes and triggered light.</sec><sec>In Mode B, when triggering laser energy is set to 10 mJ, a pulse width is 20 ns, and peak power is 0.5 MW, the switch operates at a voltage of 4.6 kV, with a short-circuit current reaching 8.5 kA and a current rise time of 66 ns, achieving a d<i>i</i>/d<i>t</i> value exceeding 129 kA/μs. The main characteristic is that the initial conduction of the switch satisfies the photonic linear conduction mode, while the later conduction exhibits the field-induced nonlinear conduction mode, thus achieving both fast-rise-time output and the capability for large current and wide pulse width, reflecting a hybrid conduction mode. This mode is suitable for high-power and wide-pulse applications, such as accelerator power supplies, its characteristics are similar to those of hydrogen thyratrons and pseudo-spark switches.</sec><sec>The discovery and validation of multiple operating modes for the switch significantly enhance the d<i>i</i>/d<i>t</i> and peak power of power semiconductor switching devices, laying a theoretical and experimental foundation for the development of semiconductor switches with ultra-high peak power. Additionally, the switching devices are packaged according to their different operating modes and have been used in accelerator power supplies, solid-state detonators, and high-stability pulse drive sources, achieving positive results.</sec>