Minority carrier lifetime and iron concentration measurements on p-Si wafers by infrared photothermal radiometry and microwave photoconductance decay.

A comparative study of electronic transport properties of p-Si wafers inten tionally contaminated with Fe was performed using infrared photothermal rad iometry (PTR) and microwave photoconductance decay (mu -PCD). Strong correl ations were found between PTR and mu -PCD lifetimes in a lightly contaminat ed wafer with no significant PTR transient behavior. The absolute PTR lifet ime values were larger than the local averaged CI-PCD values, due to the di fferent excitation wavelengths and probe depths. In a heavily contaminated wafer the mu -PCD and PTR lifetime correlation was poorer. PTR measurements were highly sensitive to Iron concentration, most likely due to the depend ence of the bulk recombination lifetime on it. Rapid-scanned (non-steady-st ate) PTR images of the wafer surface exhibited strong correlations with bot h mu -PCD lifetime and Iron concentration images in both heavily and lightl y contaminated wafers. For the lightly and uniformly contaminated wafer, PT R scanning imaging was found to be more sensitive to iron concentration and lifetime variations than mu -PCD images.