The trend of beta (the deteriorative degree of dielectric relaxation) rises from 12.1 nm, peaks at 22.5 nm with the beta value of 0.03, and then declines within the range of 22.5 to 25 nm. The trend of tau decreases from 12.1 to 25 nm accordingly, similar to the CeO2 samples. It is well known that the optical and electrical properties of CeO2 are highly dependent on the surface and interface structure, morphology, and chemistry [10], which in turn is controlled by the fabrication technique and growth conditions [11]. The ability to tailor the properties so as to optimize performance requires a detailed understanding of the relationship

between electronic and geometric structures, particularly at nanoscale dimensions, of CeO2. CeO2 readily crystallizes in the fluorite form, but control

over the grain size formed is important due to the effect of grain boundary density on properties Selleckchem PXD101 like ionic conductivity and dielectric response [12]. Moreover, the intrinsic frequency dispersion (dielectric relaxation) studies [13, 14] have also been found to be relevant to grain size of the samples, especially those dealing with nanostructured materials. In this check details paper, CeO2 is prepared by ALD under different deposition temperatures. The grain size of the samples is determined respectively by the fabrication technique and growth conditions. The focus of the present work is, therefore, on elucidating grain size effects on the electrical properties of CeO2. An interesting correlation between grain size and dielectric relaxation, which provides a reference to tailor the properties and performance of CeO2 as a high-k thin film, has been presented and discussed in the paper. Methods The CeO2 thin films were NVP-BSK805 deposited by liquid injection ALD via a modified Aixtron AIX 200FE AVD reactor (Herzogenrath, Germany) fitted with a liquid injector system. The precursor was a 0.05-M solution

of [Ce(mmp)4] (SAFC Hitech Ltd, Dorset, England, UK) in toluene [9], and the source of oxygen was deionized water. ALD procedures were run at substrate temperatures of 150°C, 200°C, 250°C, 300°C, and 350°C, respectively. The evaporator temperature was 100°C, and the reactor pressure was 1 mbar. The CeO2 thin films were grown on n-Si(100) wafers. Argon carrier gas flow was performed with Acyl CoA dehydrogenase 100 cm3/min. The flow of [Ce(mmp)4]/purge/H2O/purge was 2:2:0.5:3.5 s, and the number of growth cycles was 300. For physical characterization, X-ray diffraction (XRD) was achieved using a Rigaku miniflex diffractometer (Shibuya-ku, Japan) with CuKα radiation (0.154051 nm, 40 kV, 50 mA), spanning a 2θ range of 20° to 50° at a scan rate of 0.01°/min. Raman spectra were obtained with a Jobin-Yvon LabRam HR consisting of a confocal microscope coupled to a single grating spectrometer equipped with a notch filter and a charge-coupled device camera detector.