Frequency-scanned and lock-in common-mode-rejection demodulation schemes were used with laser infrared photothermal radiometric (PTR) detection of B+, P+, and As+ ion-implanted Si wafers, with or without surface-grown oxides. The implantation energy was 100 keV with doses in the range 1 x 10(11) -1 x 10(13) ionS/cm(2). The lock-in common-mode-rejection demodulation (CMRD) scheme exhibited superior signal resolution in all cases where the conventional frequency-scan signals were essentially overlapped. These were B+-implants in the dose range 1 X 10(12)-1 x 10(13) ionS/cm(2), and P+-implants in the 10(12) ions/cm(2) range. (c) 2005 Elsevier Ltd. All rights reserved.