Aluminium phosphide (AlP) particles are often suggested to be the nucleation site for eutectic silicon in Al-Si alloys, since both the crystal structure and lattice parameter of AlP (crystal structure: cubic F43m; lattice parameter: 5.421 A) are close to that of silicon (cubic Fd3m, 5.431 A), and the melting point is higher than the Al-Si eutectic temperature. However, the crystallographic relationships between AlP particles and the surrounding eutectic silicon are seldom reported due to the difficulty in analysing the AlP particles, which react with water during sample preparation for polishing. In this study, the orientation relationships between AlP and Si are analysed by transmission electron microscopy using focused ion-beam milling for sample preparation to investigate the nucleation mechanism of eutectic silicon on AlP. The results show a clear and direct lattice relationship between centrally located AlP particles and the surrounding silicon in the hypoeutectic Al-Si alloy.
Annealing effects on Al-Nd (0.19 -1.82 at. %) thin films deposited on a glass substrate have been investigated. It is found that the resistivity of an Al-Nd-alloy thin film decreases significantly after annealing at 300 9C or higher temperatures. Using cross-sectional transmission electron microscopy (X-TEM), we have observed segregation of Al-Nd intermetallic precipitates and pure-Al grains during the annealing. The decrease of the resistivity can be attributed to the segregation. Segregation has been also detected from the increase of diffracted X-ray intensities corresponding to Al-Nd inter-metallic compounds in X-ray diffraction (XRD) analysis. Atomic force microscopy (AFM) observation has revealed that the optimum content ratio of Nd in Al-Nd alloys used as interconnect materials for thin-filmtransistor liquid crystal display (TFT/LCD) applications is around 0.97 atomic %.
Investigation of the properties of indium zinc oxide (IZO) thin films sputter-deposited on LCD-grade glass substrate showed that the resistivity of an IZO film decreases markedly as the substrate temperature is increased from room-temperature to 120°C. This phenomenon can be attributed to the growth of In-Zn intermetallic compounds in the amorphous region as a result of annealing. The compound growth was observed by plan-view transmission electron microscopy.Although the transmittance and resistivity of IZO are inferior to those of indium-tin oxide, these disadvantages do not present any difficulties in the practical use of IZO for designing TFT-LCDs. Since IZO is an amorphous material, we propose a five-mask process with this characteristic.
In focused ion beam (FIB) fabrication of cross-sectional transmission electron microscopy (X-TEM) specimens, highly accelerated ion beams sometimes cause serious damage. The damage can be induced in both the specimen surface and in the side walls. We used X-TEM observations to investigate the side-wall damage induced by FIB fabrication in crystalline silicon. The damaged layer was found to be about 20 nm thick in the case of 30-keV FIB etching. We tried to reduce the damage by several methods, such as gas-assisted etching (GAE) with iodine, broad argon ion milling and wet etching. The damaged layer was 19 nm for GAE and 12 nm for argon ion milling with a beam current of 70 mA and the tilt angle between the beam and the specimen of 15 degrees. Wet etching using a mixture of nitric and hydrofluoric acid removes most of the damaged layer.
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