Response of InGaN/GaN multiple quantum well structure to UV-C and vacuum UV optical excitation

We report on the behavior of InGaN/GaN multiple quantum well structure during excitation in UV-C and vacuum UV spectral region. Photoluminescence excitation spectra show peaks with positions different to the peaks in absorption spectra. The very high absorption coefficient in order of 107 cm−1 at energies above 6.9 eV causes the excitation in the surface region which enhances the non-radiative surface recombination. The mechanism explains the differences between absorption and excitation spectra measured in a studied range of energies between 5.8 and 40 eV.