Fourier transform infrared surface photovoltage spectroscopy for the investigation of mid-infrared semiconductor lasers



A novel application of the surface photovoltage spectroscopy (SPS) technique, using a Fourier transform infrared (FTIR) interferometer, has been developed for the investigation of narrow-gap mid-infrared semiconductor quantum well (QW) laser structures. We demonstrate the FTIR-SPS technique at room temperature for a GaInSb/AlGaInSb type I QW laser structure, grown on GaAs, emitting in the mid-infrared at ∼4 μm, revealing an unambiguous detection of the ground and excited state transitions of the GaInSb QW, as well as the AlGaInSb barrier bandgap energy. As a further corroboration of the new technique, the FTIR-SPS spectrum of a ∼1.5 μm communication laser structure has also been measured and shown to be in good agreement with conventional grating-based electro-modulated reflectance and SPS spectroscopic measurements on this sample. A detailed numerical analysis of the room temperature FTIR-SPS results for the mid-infrared semiconductor laser structure is also presented, including a comparison with theoretical predictions of the QW transition energies. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)