Common II-VI compound semiconducting materials are stable thermodynamically with zincblende phase, while the II-O materials such as zinc oxide ͑ZnO͒ and beryllium oxide ͑BeO͒ are stable with wurtzite phase, and cadmium oxide ͑CdO͒ and magnesium oxide ͑MgO͒ are stable in rocksalt phase. This phase disharmony in the same material family laid a challenge for the basic physics and in practical applications in optoelectronic devices, where ternary and quaternary compounds are employed. Thermodynamically the zincblende ZnO is a metastable phase which is free from the giant internal electric fields in the ͓001͔ directions and has an easy cleavage facet in the ͗110͘ directions for laser cavity fabrication that combined with evidence for the higher optical gain. The zincblende materials also have lower ionicity that leads to the lower carrier scattering and higher doping efficiencies. Even with these outstanding features in the zincblende materials, the growth of zincblende ZnO and its fundamental properties are still limited. In this paper, recent progress in growth and fundamental properties of zincblende ZnO material has been reviewed.

A stable wurtzite phase of ZnO is commonly observed. In this letter, we report the growth and characterization of zinc-blende ZnO on GaAs(001) substrates. The ZnO films grown on GaAs(001) substrates using microwave-plasma-assisted metalorganic molecular-beam epitaxy were characterized by reflection high-energy electron diffraction, x-ray diffraction, transmission electron microscope, and atomic force microscope measurements. The use of a ZnS buffer layer was found to lead to the growth of the zinc-blende ZnO films. Although the zinc-blende ZnO films were polycrystalline with columnar structures, they showed bright band-edge luminescence at room temperature.

No abstract

Thickness-dependent strain relaxation and its role on exciton resonance energies of epitaxial ZnO layers grown on 6H-SiC substrates have been studied. The magnitudes of strain were determined experimentally by x-ray diffraction measurements. The strain ratios under biaxial stresses (Δc/c0)/(Δa/a0) of epitaxial ZnO layers grown on SiC and Al2O3 substrates were estimated to be 0.38 and 0.50, respectively. The strain-induced band shift δEA/δεzz for ZnO/SiC and ZnO/Al2O3 heterostructures was analyzed by photoluminescence with the values of 13.1 and 14.6 eV, respectively. These comparative strain-induced band shifts, as well as Poisson ratios, evidenced the role of lattice deformation kinetics induced by different lattice mismatches in the ZnO/SiC and ZnO/Al2O3 heterostructures.