Growth and Characterization of Zinc-Oxide Films Grown by UsingPlasma-Assisted Molecular Beam Epitaxy on (111) SiliconSubstrates with Ti and Titanium Compound Buffer Layers

摘要

The possibility of sputter-deposited Ti and processed Ti compounds as buffers for the growthof epitaxial ZnO films on (111) Si substrates by using plasma-assisted molecular beam epitaxy(PAMBE) were studied. We used four types of substrates: 1) a bare (111) Si substrate, 2) an as-deposited Ti/Si (111) substrate, 3) Ti/Si (111) substrates nitrided or oxidized by using an electricfurnace under a N_2or an Ar+O_2ambient and 4) Ti/Si (111) substrates treated with a N or anOplasma in the PAMBE chamber. The ZnO films were not single crystalline, but grew with ahighly preferred orientation along the <0001> direction. The buffers investigated in this studywere effective in improving the crystal quality of the ZnO films on (111) Si substrates althoughsingle-crystalline ZnO films were not grown. Among the investigated samples, the ZnO film on theoxidized Ti/Si substrate had the narrowest X-ray rocking curve (XRC) with a Full width at halfmaximum (FWHM) of 3.05° while the ZnO film on the bare Si substrate showed a very broad XRCwith a FWHM of 11.793°. We expect that epitaxial or high-quality Ti oxide may be a promisingbuffer for the growth of high-quality, epitaxial ZnO films on (111) Si substrates.