Novel cubic ZnxMg1−xO epitaxial heterostructures on Si (100) substrates

We have synthesized a new cubic phase of ZnxMg1−xO alloy which can be grown epitaxially on MgO (100) by lattice-matching epitaxy, and on Si (100) substrate by our domain-matching epitaxy for integration with silicon microelectronic devices. Cubic ZnxMg1−xO films on MgO (100), Si (100) and α-Al2O3 (0001) substrates were grown using a rotating target in a single chamber ‘in situ’ pulsed-laser deposition system. Integration of ZnxMg1−xO films with silicon was done via titanium nitride (TiN) buffer layers where four lattice constants of TiN match with three of the silicon during epitaxial growth via domain epitaxy. Rutherford backscattering/ion channeling techniques were used to determine chemical composition and crystalline quality of the films for x=0.0–0.18. Detailed X-ray diffraction and transmission electron microscopy studies confirmed the epitaxial nature of ZnMgO/MgO (100) and ZnMgO/TiN/Si (100) heterostructures, and showed the formation of the Mg2−xZnxTiO4 spinel at the interface with TiN. Using optical transmission measurements, the band gap of cubic Zn0.18Mg0.82O film was estimated to be approximately 6.7 eV. The potential use of these alloys for optical devices in the ultraviolet range is discussed.