Dynamic carrier lifetime imaging of silicon wafers using an infrared-camera-based approach

We present a calibration-free dynamic infrared carrier lifetime mapping technique, yielding images of the carrier lifetime of multicrystalline silicon wafers within seconds. Images of the infrared emission of the sample under test are taken directly after switching on a monochromatic illumination source and after steady-state conditions have been established in the sample. Making use of the proportionality between the infrared emission and the free carrier density inside the sample, the carrier lifetime is calculated from the signal ratio of these two images by an analytical method. We achieve an excellent agreement when comparing our results with carrier lifetime mappings obtained by the microwave-detected photoconductance decay technique. (C) 2008 American Institute of Physics.