利用微波吸收技术对Si衬底上微晶及纳米β-SiC薄膜的过剩载流子瞬态行为进行了分析.所用样品采用PECVD技术制备,微波吸收测量采用脉宽35 ps,波长355 nm脉冲激光.所测得的载流子浓度衰减分为快、慢2个过程,微波吸收瞬态特性满足双指数衰减规律.该结果表明,样品光生载流子衰减过程主要决定于2种陷阱作用,其中快过程与SiC薄膜中浅能级陷阱的载流子弛豫效应相关,而慢过程则是深能级陷阱的载流子弛豫行为占优势的结果.纳米碳化硅晶粒界面较高的缺陷态密度导致载流子俘获几率增加,非辐射复合几率减小,纳米β-SiC薄膜表现较长的载流子衰减时间.
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