Mid-Infrared Intersubband Absorption in Strain-Balanced Non-Polar (In)AlGaN/InGaN Multi-Quantum Wells

Strain-balanced non-polar m-plane (In)AlGaN/InGaN quantum wells are shown for the first time to exhibit mid-infrared intersubband absorption in the 3.4-5.1m range. A series of samples was grown using plasma assisted molecular beam epitaxy as an alternative to high Al-composition non-polar m-plane AlGaN/GaN quantum wells. The structural properties of the samples were determined using high resolution x-ray diffraction and transmission electron microanalysis. The experimental intersubband transition energy of each sample was measured using direct and attenuated total reflection Fourier transform infrared spectroscopy and compared to energies calculated using local-density and Hartree-Fock approximations. The effect of different material parameters such as quantum well width, barrier alloy, and charge density on the transition energy is explored to determine the potential of this material for practical applications.