Correlation of native defects between epitaxial films and polycrystalline BaSi2 bulks based on photoluminescence spectra

We conducted photoluminescence (PL) measurements at 8 K on BaSi2 epitaxial films and polycrystalline bulks. PL intensities were enhanced for films grown at 650 °C compared to those at 580 °C due to the reduction of carrier recombination centers. The PL spectra were fitted well by four Gaussian curves peaking at almost the same energies regardless of the film and bulk forms. Their contribution changed depending on the Ba-to-Si atomic ratio in BaSi2. Based on the PL spectra and defect levels acquired by deep-level transient spectroscopy, we established a model for radiative defects which stem from intrinsic defects such as Si vacancies.