ABSORPTION OF INGAN SINGLE QUANTUM-WELLS DETERMINED BY PHOTOTHERMAL DEFLECTION SPECTROSCOPY

Photothermal deflection spectroscopy (PDS) is used to study the absorp tion of GaN/InGaN/GaN double heterostructures in the energy range from 0.6 to 3.8 eV. The heterostructures containing 1-77-nm-thick InGaN si ngle quantum wells were deposited by chemical vapour deposition from o rganometallic precursors. They are measured to investigate the absorpt ion coefficient, bandgap, indium concentration and fluctuation of the quantum wells. A bandgap increase of hexagonal InxGa1-xN (x approximat e to 0.14) of 60 meV is observed with decreasing well thicknesses from 15 to 1 nm. The distribution of In-concentration of the InxGa1-xN lay ers was estimated from the slope of the absorption coefficient versus photon energy for energies below the bandgap and found to be Gaussian with a full width of half maximum of Delta x = 0.03.