Growth of ZnO Films on Si(111) by Metalorganic Chemical Vapor Deposition with AlN and Low-Temperature ZnO Double Buffers

Abstract

To enhance the quality of ZnO films on Si(111) substrate, single layers of low-temperature ZnO (LT-ZnO) and AlN, as well as a combination of AlN and LT-ZnO layer, were used as intermediate layers by atmospheric pressure metalorganic chemical vapor deposition system. Only polycrystalline ZnO film was formed when a LT-ZnO single buffer was used. Crystal quality was enhanced when LT-ZnO was replaced by 20 nm AlN as the single buffer. The full width at half maximum (FWHM) of ZnO(0002) x-ray diffraction ω-rocking curve was 642 arcsec. Cracks began to appear on the film surface as crystallinity was enhanced. A ZnO mosaic single-crystal film with a mirror-like surface was successfully fabricated when a combined AlN and LT-ZnO served as buffer, and its FWHM of ZnO(0002) ω-rocking curve peak was only 460 arcsec. The film surface was smoother but cracks were still evident on the film. Contrary to the three-dimensional growth mode of samples with a single buffer, a quasi-two-dimensional growth mode was realized for the double-buffered high-temperature ZnO layer. Calculated film thickness was 2.14 μm, and the growth rate reached 4.3 μm/h based on the laser in situ laser reflectance trace.