重离子辐照1200V碳化硅二极管漏电退化的缺陷分析

目的研究1200 V碳化硅二极管重离子辐照诱生缺陷对漏电流退化的影响。方法以SiC结势垒肖特基二极管(Junction Barrier Schottky Diode,JBSD)为样品,采用能量为208 MeV,LET=37.3 MeV·cm^2/mg的锗离子进行辐照试验,利用半导体器件分析仪对重离子辐照前后1200 V SiC二极管的电学特性进行测试,利用深能级瞬态谱仪(Deep Level Transient Spectrum,DLTS)进行缺陷分析。结果辐照后,二极管的正向IV特性和CV特性未发生明显变化,反向IV特性退化。DLTS测试结果显示,E0.4能级和Z1/Z2能级基本未发生变化,EH能级有展宽的现象。测试电压VM=-8 V,填充脉冲电压VF=-1 V条件下测得的EH能级浓度比VF=-4 V条件下测得的高。结论分析认为,EH能级的缺陷复杂,推测是两个或多个缺陷能级的叠加(EH4、EH5、EH6、EH7等),此处缺陷的复杂程度与漏电流的退化成正相关,且这些缺陷的所在位置接近SiC外延层的表面。

Failure Analysis on Leakage Current Degradation of Heavy-ion-irradiated 1200 V Silicon Carbide Diodes

The paper aims to study the influences of defects induced by heavy ion irradiation on leakage current degradation of 1200 V SiC diode. SiC Junction Barrier Schottky Diode (JBSD) was used as the sample. Germanium ion with energy of 208 MeV and LET=37.3 MeV.cm2/mg was used for irradiation test. The electrical properties of 1200 V SiC diodes before and after heavy ion irradiation were tested with a semiconductor device analyzer, and the defect analysis was carried out with a Deep Level Transient Spectrometer. After irradiation, the forward IV and CV characteristics of the diode did not change significantly, and the reverse IV characteristics were degraded. DLTS results showed that the E0.4 energy level and Z1/Z2 energy level were basically unchanged, and the EH energy level was broadened. The concentration of EH energy level measured under the test voltage VM=-8 V and filling pulse voltage VF=-1 V was higher than that measured under VF=-4 V. It is concluded that the defects of EH energy level are complex, presumably the combination of two or more defect energy levels (EH4, EH5, EH6, EH7, etc.). The complexity of defects is positively correlated with the degradation of leakage current, and the locations of these defects are close to the surface of SiC epitaxial layer.