Simulation And Experimental Researimental Research On The Structure Of Gan Photoconductive Switch

GaN materials have strong critical breakdown electric field,low dielectric constant,high dark state resistivity,high electron saturation speed and other performance characteristics,and have great development prospects in the field of ultra-fast power pulses.This paper simulates and optimizes the structure of GaN photoconductive switches and experimentally studies the optical properties of GaN photoconductive switches.Firstly,based on the device simulation software,the interface switch structure of the coplanar surface electrode Si3N4,the interface switch structure of the different surface electrode Si3N4,the air interface switch structure of the coplanar surface electrode and the air layer switch structure of the different surface electrode are modeled and simulated,the air interface layer switch structure of the coplanar surface electrode,and the air interface layer switch structure of the different surface electrode.Their advantages and disadvantages in voltage withstand and photoelectric conversion are analyzed,and parameters such as trigger position,bias voltage and spot diameter are optimized respectively.In the simulation,the electrical pulses of the four structures are compared:the photoconductive switch covered with Si3N4 interface layer has better voltage resistance,and the electrode structure of the different surface electrode is better than the electrode structure of the coplanar surface;the switch does not add light and A comparison of the electric field distributions generated by the light shows that the space charge electric field generated by the separation of photo-generated carriers increases the distribution of the electric field in the switch;the four-structure switch shows that the different-face electrode structure can withstand higher voltages,which is not easy to reach the breakdown point;through the lateral trigger position optimization simulation,the pulse width of the electrical pulse increases as the light trigger position approaches the cathode;The simulation results show that when the light source is located on the left side of the GaN substrate from the near negative and anode side to the far negative and anode side,the pulse impulse increases gradually,but the pulse width becomes wider.Secondly,the correctness of the simulation results was verified by pump light experiments at 355 nm and 532 nm;the Ga-side,N-side reflectance,transmittance,and absorbance of the SI-GaN:Fe photoconductive material 0001 crystal phase thickness of 350 μm and 500 μm,respectively,were studied;11-22 The reflectance,transmittance and absorbance of the two surfaces with a crystal phase thickness of 350 μm.The experiment found that the GaN:Fe material of the 11-22 crystal phase has a large difference between the Ga and N planes.