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 correla tions were found between PTR and mu-PCD lifetimes in a lightly contaminated wafer with no significant PTR transient behavior. The absolute PTR lifetim e values were larger than the local averaged mu-PCD values, due to the diff erent excitation wavelengths and probe depths. In a heavily contaminated wa fer the mu-PCD and PTR lifetime correlation was poorer. PTR measurements we re highly sensitive to iron concentration, most likely due to the dependenc e of the bulk recombination lifetime on it. Rapid-scanned (nonsteady-state) PTR images of the wafer surface exhibited strong correlations with both mu -PCD lifetime and [Fe] concentration images in both heavily and lightly con taminated wafers. For the lightly and uniformly contaminated wafer, PTR sca nning imaging was found to be more sensitive to iron concentration and life time variations than mu-PCD images. (C) 2000 American Institute of Physics. [S0021-8979(00)08111-1].