Controlled texture of reactively rf-sputtered ZnO thin films

Abstract

Detailed analysis by reflection electron diffraction (RED), x-ray diffraction (XRD), and scanning electron microscopy (SEM) was performed on thin ZnO layers which were formed under reactive and nonreactive rf-sputtering conditions. A variety of textures and morphologies were observed. 100% reproducible piezoelectric layers, preferred oriented with [002] perpendicular to the layer within 7°, could be obtained by reactive sputtering from a zinc target at rf power of 150 W, oxygen-argon atmosphere of 8×10−3 Torr with 35% O2, and with the glass substrate being kept at room temperature by a cooling device. No differences in the surface-acoustic-wave properties were found between reactively and nonreactively sputtered ZnO layers which had similar texture and morphology. SEM techniques proved to be extremely misleading in the study of this type of layer; there is no relationship between an observed columnar structure and the texture of the layer which is determined by RED, and also between the column thickness (∼1 μm) and the actual crystallite size (∼200 Å) which is determined by XRD. It is shown that the observed columns must be polycrystalline.

Planar defects in ZnO thin films deposited on optical fibers and flat substrates

“…The occurrence of these columnar microstructures has been confirmed by several studies that have employed scanning electron microscopy (SEM). [16][17][18][19] X-ray diffraction (XRD) has been used to determine that the columnar grains tend to exhibit a preferred orientation with the plane of a planar substrate. The standard deviation of the x-ray diffraction rocking curve of the 0002 diffraction peak (s0002) is commonly used to characterize the degree of [0001] texture, which is dependent on deposition conditions and the substrate material.…”

Fabrication and properties evaluation of aluminum and ruthenium co-doped zinc oxide thin films

“…As sputtering power density increasing to 6.1 W/cm 2 , the film showed a less crystalline with a random orientated structure. The full width at half maximum (FWHM), the width at half the maximum peak intensity, is inversely proportional to the crystal size and can be related to the quality of crystallinity in columnar polycrystalline thin films [33]. Fig.…”

Effect of Ru addition on the properties of Al-doped ZnO thin films prepared by radio frequency magnetron sputtering on polyethylene terephthalate substrate

“…The full width at half maximum (FWHM), the width at half the maximum peak intensity, is inversely proportional to the crystal size and can be related to the quality of crystallinity in columnar polycrystalline thin films [29]. Fig.…”