Photoinduced defects in $a$-Si:H Films and InGaN/GaN multiple quantum well structures doped with Eu, Sm, and Eu + Sm

Photoinduced defects in $a$-Si:H films arise due to an increase in the density of midgap states when weak strained silicon–hydrogen (Si–H) bonds transform to dangling Si–Si bonds and also due to the presence of separate regions with different densities and types of Si–H bonds. In rare-earth-doped InGaN/GaN multiple quantum well structures, defects are induced as a result of increasing the luminescence excitation intensity in taking microphotoluminescence spectra. This complicates the spatial relief of the random potential mainly in the lateral plane and may result in clustering, with In content in the clusters differing from the mean value, and even precipitation of the InN and GaN phases.