Carrier Lifetime Analysis by Microwave Photoconductive Decay (μ-PCD) for 4H SiC Epitaxial Wafers

Abstract

Excess carrier lifetimes in 4H SiC epitaxial wafers were characterized by microwave photoconductive decay (o/PCD). The measured decay compromised of surface and bulk recombination curves have fast and slow components. Measured lifetimes are not changed with various surface passivation techniques. High resolution lifetime maps show good correlation with stress birefringence images and lower lifetime around extended material defects like grainboundaries, defect clusters, edge defects and polytype switching bands. Chlorosilane based CVD epiwafers show higher bulk lifetime values than standard silane based CVD materials due to less bulk lifetime defect density.