If you are looking for high-quality products, please feel free to contact us and send an inquiry, email: brad@ihpa.net
Magnesium zinc oxide (MgxZn1-xO or MZO) is an important candidate material for a variety of emerging optoelectronic applications. This is because of its wide direct band gap and bright room-temperature luminescence. It also possesses the highest piezoelectric tensor of the tetrahedrally bonded semiconductors, which enables ultrafast electromechanical effects and large nonlinearities [1,2].
The MgxZn1-xO thin films investigated here were deposited on room temperature soda lime glass (SLG) substrates by magnetron co-sputtering of MgO and ZnO targets and subsequently annealed. Complex dielectric function spectroscopic ellipsometry (SE) measurements reveal that the MZO films are dominantly in the wurtzite phase with a bandgap that is increasing from 3.264 to 3.826 eV as the Mg atomic fraction x increases over a range of 0
This bandgap behavior is in excellent agreement with a quadratic relationship deduced from SE data based on a least-squares analysis using structural and optical models that incorporate photon energy independent variables of thicknesses that describe the MZO structure and oscillator parameters. The best fitting variable oscillator parameters show smooth dependences on the Mg composition x.
X-ray diffraction patterns of the annealed MZO samples reveal broad peaks that indicate poor crystallinity and a mixture of wurtzite and cubic rocksalt phases. However, the lattice parameter c of the MZO thin film decreases continuously with increasing x in accordance with a substitutional solid solution of the two phases in the amorphous Mg-Zn-xO matrix. This result is consistent with the Mg atoms being substituted for Zn at Zn lattice sites in a wurtzite-like phase.