Wafer Level Recombination Carrier Lifetime Measurements of 4H-SiC PiN Epitaxial Wafers

Effective recombination lifetimes of 4H-SiC PiN epitaxy wafers are measured by mu-PCD (microwave photoconductive decay) system at wafer level. Lifetimes measured in presence and absence of the p(+) layer show lower lifetime values with p(+) layer present. This is attributed to high recombination rate at p(+)/n(-) interface. Lifetimes at various buffer thicknesses show lower values at the buffer layer of about 50 mu m due to high interface recombination rate resulting from rougher surface of the buffer layer. Lifetimes of PiN wafers from interrupted and Continuous p+/n- growth are very comparable.