Characterization of wurtzite Zn1−xMgxO epilayers grown on ScAlMgO4 substrate by methods of optical spectroscopy

Abstract

Wurtzite Zn1−xMgxO epilayers (x = 0, 0.26, 0.44, 0.49, 0.66) grown by the plasma-assisted molecular beam epitaxy on ScAlMgO4 substrate were characterized using the methods of optical spectroscopy: spectroscopic ellipsometry (SE), optical absorption (OA), and photoluminescence (PL). The complex dielectric function in the spectral range of 210–1690 nm, band gap width, exciton absorption and emission parameters, and film quality were studied and discussed. Individual characterization of samples was provided by combining SE and OA measurement results. The observed increase of the band gap up to 4.35 eV with the rise of the MgO content allowed the recommendation of the wurtzite Zn1−xMgxO epilayers as material for UV sensors. The origin of defects hampering the practical application of the materials was discussed.