XTEM investigation of recovery on electrical degradation of 4H-SiC Schottky barrier diode by swift heavy (209)~Bi ions irradiation

摘要

The recovery of electrical degradation of 4H-SiC Schottky barrier diode (SBD) by swift heavy (209)~Bi ions irradiation has been revealed in previous work. In present work, the results of cross section transmission electron microscopy (XTEM), selected area electron diffraction patterns (SAED), energy dispersive X-ray spectroscopy (EDX)line scan investigations and energy EDX mapping micrographs of the Al/WO/WTi/ TiO_2/4H-SiC SBD before and after (209)~Bi ions irradiation are given to explain the mechanism of the recovery on electrical degradation. XTEM examinations show that the swift heavy ions (SHI) cause the crystal structure to be destroyed at metal-semiconductor (M-S) interface at fluence of 1 x 10~9 ions/cm~2, which can be recovered for a certain extent at fluence of 1 x 10~(10) ions/cm~2 due to the healing effect accumulation of intense energy deposition during SHI irradiation. Furthermore, the SHI induced recrystallization at M-S interfaces, which is in good agreement with our previous results.EDX line scans reveal that the varied information of Si atoms in the WO and WTi layers after irradiation, which can be attributed to the migration of the Si towards interface after the Si-C bond destroyed by SHI. The recovery of the ration between silicon and carbon atoms plays important role in the recovery of electrical degradation at interfaces between TiO_2 and 4H-SiC.