Preparation And Propetries Of SiC Photoconductive Switch

The photoconductive switch, which is also called photoconductivesemiconductor switch (PCSS)，has excellent performances such as negligible triggerjitter time, high response speed, high-power, high-temperature stability，low powerconsumption, low parasitic inductance, high-frequency and wide-dynamic range. Italso have small size and simple structure characteristics. So the researchers pay greatattention to the photoconductive switch, it has become a promising electronic devicein the field of pulse power application technology. Silicon carbide is considered to bethe most suitable material for ultrafast, high-power, high-temperaturephotoconductive switch. Its wide band gap, high breakdown field，high dielectricstrength, high thermal conductivity, and high radiation tolerance properties offer theopportunity to reach higher switching voltages and longer lifetimes than thetraditional photoconductive switch materials. Nowadays, the growth techniques oflarge size，high quality single crystal SiC is increasing mature, it will be large-scaleused in pulse power devices, microelectronic devices. In this paper, we usesemi-insulating silicon carbide as substrate to fabricate PCSS, SiC PCSS willdefinitely have good prospects in high-speed, high-power field.Firstly, we briefly introduced the research background of SiC PCSS, the workingprinciple of PCSS and its development history. We studied the SiC material and itsinfluence on PCSS. Then, according to a large number research literature results, wedesigned the technology roadmap, which can help us research the SiC PCSS.According to the technology roadmap. the Ti electrodes were deposited on(000-1) face of n-type4H-SiC by magnetron sputtering. We investigated the effect of electrodes placement method during the annealing treatment on the contact property.When the electrodes were faced the Si tray and annealed, they showed ohmicbehavior, otherwise they showed non-ohmic behavior. X-ray diffraction (XRD), X-rayphotoeiectron spectroscopy (XPS)，scanning electron microscopy (SEM) and atomicforcc microscope (AFM) were used to characterize the electrode phase, composition,thickness and surface morphology. The additional silicon introduced from the Si trayplayed a key role in the formation of ohmic contact on Ti/4H-SiC. We also preparedthe Si/Ti/SiC and Ni/SiC ohmic contact, respectively on C-face and Si-face SiC.. Thelinear transmission line model (TLM) was used to calculate the specific contactresistance pc, the surface morphology was characterized by AFM and SEM,respectively.In this paper, we based on the research work of the ohmic contacts, then weprepared the transverse structure photoconductive semiconductor switch based on thesemi-insulating silicon carbide substrate, and analyzed the related theory of the SiCPCSS. According to the characteristics of the SiC FCSS, we setted up a test platform,which used the532nm wavelength Nd:YAG laser as the trigger source. In this article,we studied electrical performance of the transverse structure SiC PCSS. The fallingedge of the PCSS current pulse time was less than3ns, the ring time was less thanI3ns? the pulse width of the PCSS was stability in12ns, which was consistent with thetrigger pulse width of the laser.