4H-SiC衬底电化学氧化行为研究

Study on electrochemical oxidation behaviors of 4H-SiC substrate

为了提高电辅助加工技术用于碳化硅(SiC)衬底的加工效果,系统地研究了p型4H-SiC在硫酸钠溶液中的电化学氧化行为。结果表明,该单晶SiC的载流子浓度为2.0×10^(13)cm^(-3),平带电位为0.8 V_(SCE)。通电后,SiC被氧化为中间产物,之后继续氧化为二氧化硅(SiO_(2))。在0~9 V_(SCE)的电位范围内,SiC的阳极氧化经历4个阶段:活化区、钝化区、过渡区和过钝化区,且随着电位的增加,氧化速率增加;当电位高于击穿电位(约7.4 V_(SCE))即电位处于过钝化区时,SiC表面钝化膜被破坏且表面发生孔蚀(孔的深度约为0.069μm)。该结果为提高电辅助加工效果提供参考。

To improve the effect of the electro-assisted processing technology for the efficient processing of silicon carbide(SiC)substrates,the electrochemical oxidation behavior of p-type 4H-SiC in sodium sulfate solution is systematically investigated.It is found that the current carrier concentration of the single-crystal SiC is 2.0×10^(13)cm^(-3)and the flat-band potential is 0.8 V_(SCE).SiC has been oxidized to intermediate products after powering on and then to silica.At a potential range of 0 to 9 V_(SCE),the anodic oxidation of SiC experiences four stages:active zone,passive zone,transient zone and tarns-passive zone.The oxidation rate increases as the potential increases.Moreover,the passivation film of SiC surface is destroyed and pitting corrosion occurs with a hole depth of about 0.069μm when the potential is higher than the breakdown potential(about 7.4 V_(SCE)),that is,the potential stays in the tarns-passive zone.This result provides a reference for improving the processing effect of electro-assisted processing.