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Highly c-axis oriented ZnO films have been deposited onto Si (100) substrates at room temperature (RT) and 750 degrees C using radio-frequency reactive magnetron sputtering. The films have been characterized with X-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM). It is found that the film deposited at RT has grains with a regular shape while the grains show an irregular shape at 750 degrees C. Both of the films deposited at RT and 750 degrees C have a crystallographic orientation relationship with the Si substrate, [110](Si)//[100](ZnO) and (001)(Si)// (001)(ZnO) with a deviation angle below 3 degrees. Cross-sectional TEM images reveal that both of the ZnO films deposited at RT and 750 degrees C are composed of two layers. The first layer is a ZnO transition layer on the Si substrate and the second is a high c-axis oriented layer above the transition layer. The effects of substrate temperature on the growth behavior of ZnO films are discussed. (C) 2006 Elsevier B.V. All rights reserved.

We investigated the properties of a Ge–Bi–Te ternary chalcogenide thin film which was deposited on a SiO2/Si substrate by varying RF-sputtering power on the GeTe and Bi target. The aim was to search for an appropriate candidate for a new phase change memory. Various analyses are conducted in order to investigate the composition, phase separation, and crystallization behavior of the Ge–Bi–Te alloy. The XRD results of each annealed sample showed that the Ge–Bi–Te alloy crystallized into Ge2Bi2Te5, GeBi2Te4, GeBi4Te7 phase at around 300 °C according to Ge content and expelled amorphous Ge crystallized as a single phase over 400 °C. Combining these with the differential scanning calorimetry (DSC) results, we demonstrated that Tc and Tm of the Ge–Bi–Te alloy are respectively higher and lower than those of conventional Ge–Sb–Te (GST) films. All the phases, including not only various Ge–Bi–Te ternary phases but also the Ge phase crystal structure, were also confirmed with high-resolution transmission electron microscopy (HR-TEM) images and diffraction patterns. It is noted that some of the Ge2Bi2Te5 grains show specific facetted planes such as {0113}, {0112}, and {0001}. Through successive analyses, we revealed the structural evolution of the Ge–Bi–Te alloy according to Ge contents and confirmed the potential of the Ge–Bi–Te alloy for phase-change random access memory (PRAM) applications.

Zn1−xCdxO films (0⩽x⩽0.179) were grown on Si (001) substrates at 750°C with a radio-frequency reactive magnetron sputtering method. Difference between the photoluminescence (PL) spectra taken at room temperature (RT) and at 12K is reported and is deduced to be the result of PL emission from the ZnCdO phases with wurtzite and zinc blende structures. It is also found that the RT PL intensity is in inverse proportion to the carrier concentration in the films. Cd incorporation results in the transform of conductivity from p type to n type and a decrease of carrier mobility.

Using reactive radio-frequency magnetron sputtering, epitaxial growth of ZnO film was observed on Si (001) substrate at different temperatures ranging from room temperature to 750°C. The epitaxial relationship was determined to be ZnO(001)‖Si(001) in the direction normal to the surface of the films with a deviated angle less than 3° and ZnO[100]‖Si[110] or ZnO[310]‖Si[110] in the plan view. Based on (2×1) reconstruction of Si (001), a heteroepitaxial model was suggested to discuss the influence of Si (001) substrate on the growth and morphology of ZnO films at different temperatures.

Wurtzite ZnO∕MgO superlattices were grown on Si (001) substrates at 750°C with a radio-frequency reactive magnetron sputtering method. X-ray diffraction analysis revealed the superlattice to be a highly textured ZnO (001) layer and to be of high crystallinity and homogeneity in thickness. The periodic layer thickness was determined to be 1.85–17.72nm. Room-temperature photoluminescence was detected for all the samples and showed that the blueshift varied with the well width of the ZnO layer, being consistent with the expectation of quantum-size effect.