The Investigation Of Nanosecond Pulse Generated By Si-GaAs Body Avalanche

Switching technology plays an important role in pulsed power technology. The parameters and characteristics of switching elements have the most direct influence on the rise time and amplitude of pulse. High repetition frequency?miniaturization and all-solid state are the main development trend of current switching technology. Therefore, the research of switching devices with high voltage and high current, fast breakdown, long life and stable operation under repeated pulses are very important direction in current pulse power technology at China and abroad.When investigating the breakdown characteristics of semi-insulating GaAs, we found that semi-insulating GaAs can be turned on at an average electric field of 20 kV/cm under sharp electrode conditions. After further study on the shape of the electrode, we achieved a semi-insulating GaAs sample avalanche to generate nanosecond electric pulses. In this paper,the effects of energy storage capacitor, pressurization mode, temperature, coaxial energy storage,secondary acceleration and sample series on pulse output are analyzed, and the triggering mechanism of pulse is analyzed. Mainly completed the following work:(1) The optimal working mode of semi-insulating GaAs body-avalanche samples was investigatedOn the basis of measuring the voltammetric characteristic curve of semi-insulating GaAs samples, we designed capacitor storage circuit to generate nanosecond high voltage electric pulse. Through the research of storage capacitor, pulse pressure and temperature's effects on pulse output, the best mode of semi insulating GaAs samples were determined. The pulse voltage method has better stability than the manual, so the pressurization mode should use the pulse voltage method.In pulse voltage method, the pulse width and output voltage can not have better parameters at the same time. We produce a narrow pulse by selecting a small capacitor and high voltage pulse output by selecting a large capacitor. In the pulse voltage mode, the output pulse width at the low temperature is narrower, the rising edge is faster and the voltage is larger. In summary, the semi-insulating GaAs body avalanche sample to produce nanosecond electric pulse of the best working conditions: pulse voltage compression, the sample at low temperatures,choosing a small energy storage capacitor. The semi-insulating GaAs samples with a 600um electrode gap in the pulse voltage mode, resulting in a minimum pulse width of 2.923ns, voltage of 433V, the rising edge of 1.391ns, and the maximum voltage of 1185V, pulse width of 12.95ns, rising edge of 3.149ns nanosecond narrow pulse.(2) The effects of coaxial line energy storage, secondary compression and three samples on the waveform are studied.The coaxial cable energy storage circuit is used to obtain an approximate square wave pulse with a rising edge of several nanoseconds. The width of the pulse is proportional to the length of the coaxial cable.Choosing the appropriate coaxial cable length and capacitance parameters and different combinations,can get different waveforms,but the coaxial cable will increase the circuit size. The secondary compression mode compresses the input pulse, using a secondary compression mode to a pulse width of 1.867 ns and a rising edge of 1.332 ns, but the output voltage is low. The samples in series can improve the withstand voltage, and the output voltage is higher than the output voltage of a single sample, and the pulse width becomes narrower and the rising edge becomes faster.(3) The triggering mechanism of semi-insulating GaAs self-breakdown samples was analyzed.After calculation and analysis, the mechanism of thermal conduction of the semi insulating GaAs sample is ruled out The mechanism of generating nanosecond narrow pulses is mainly related to EL2 deep level electron capture mechanism, transfer electron effect, EL2 deep level collision ionization effect and reverse gunn dipole domain.The semi-insulating GaAs body avalanche sample produces nanosecond electric pulse,which is a new method to generate high-voltage narrow pulse. It is expected to achieve high-frequency high-voltage nanosecond pulse in the form of body avalanche, for pulse power technology and solid switch technology field to add new vitality.