The measurements of photoexcited excess carrier lifetime and activation energies in a semiconductor are useful in the characterization of the quality of semiconductor materials and in evaluating the performance of working semiconductor devices. The noncontact method of photothermal infrared radiometry (PTR), with both frequency-domain (PTR-FD) [1–3] and rate-window (PTR-RW) [4,5] detection configurations has been shown to be promising for remote on-line or off-line impurity/electronic defect diagnostics. A new PTR deep-level transient spectroscopy (PTR-DLTS) which combines the PTR-RW with semiconductor temperature ramping has been developed recently [6] and found to possess high spectral peak separation and spatial resolution.