Measurement of optical absorption in single quantum wells using photothermal deflection spectroscopy

We report the measurement of the optical absorption spectra of single quantum wells of GaAs (104 Å thick) and InGaAs (75 Å thick) by photothermal deflection spectroscopy. The room-temperature spectra show distinct structure due to heavy- and light-hole excitons in both GaAs and InGaAs samples. The measurements also show that absorption spectra in extremely thin (<10 Å) quantum wells, single heterostructures, or other microstructures with very small absorptance can be obtained by this technique.