Recently, a powerful method of photothermal detection was reported which enabled thermal wave imaging to be carried out on micron sized structures in semiconductors [1,2]. The new method utilized the photothermally induced modulation of the sample’s surface optical reflectivity to detect thermal wave phenomena at bandwidths exceeding 10 MHz. The wide bandwidth capabilities of the method enabled very shallow structures to be analyzed in semiconducting materials because of the relationship that exists between the modulation frequency of the excitation beam and the thermal diffusion length.