Photothermal deflection spectroscopy of InGaAs/InP quantum wells

Abstract

The authors report on photothermal deflection spectroscopy (PDS) experiments for InGaAs/InP heterostructures. The apparatus is simple, yet sufficiently sensitive to register the heating by photon absorption for a single quantum well on a substrate with considerable thermal mass (thickness approximately=400 mu m). The PDS measurement accounts for the non-radiative relaxation after optical excitation. The extent to which the spectral dependence of the PDS signal at room temperature follows the absorption spectrum allows an estimation of the fraction of non-radiative processes. The large dynamic range of PDS and the ease of calibration of the signal permit one to measure quantum well absorption in the proper units.