In recent years, many investigators have reported visible photoluminescence from structures that consist of Ge or Si nanocrystals embedded in a SiO2 matrix deposited or grown on various substrates. We have developed a rapid technique for studying the through-thickness microstructure of this class of materials via atomic force microscopy (AFM) and, using this technique, we report on the precipitation and growth of Ge crystallites formed via a two-step process of hydrothermal oxidation of Si1−xGexO2 (x=0.15) at 450–500 °C and subsequent chemical reduction in forming gas (85/15: N2/H2; 800 °C). The Ge-particle distributions obtained with this AFM cross-sectional technique are consistent with those previously reported using other techniques. The utility of cross-sectional AFM for the evaluation of nanoscale features in the thickness of a thin film is evaluated.

A thermal microprobe has been designed and built for high resolution temperature sensing. The thermal sensor is a thin-film thermocouple junction at the tip of an atomic force microprobe ͑AFM͒ silicon probe needle. Only wafer-stage processing steps are used for the fabrication. For high resolution temperature sensing it is essential that the junction be confined to a short distance at the AFM tip. This confinement is achieved by a controlled photoresist coating process. Experiment prototypes have been made with an Au/Pd junction confined to within 0.5 m of the tip, with the two metals separated elsewhere by a thin insulating oxide layer. Processing begins with double-polished, n-type, 4 in. diameter, 300-m-thick silicon wafers. Atomically sharp probe tips are formed by a combination of dry and wet chemical etching, and oxidation sharpening. The metal layers are sputtering deposited and the cantilevers are released by a combination of KOH and dry etching. A resistively heated calibration device was made for temperature calibration of the thermal microprobe over the temperature range 25-110°C. Over this range the thermal outputs of two microprobes are 4.5 and 5.6 V/K and is linear. Thermal and topographical images are also obtained from a heated tungsten thin film fuse.

In this study, Si1-xGexO2 was produced by hydrothermal oxidation of Si1-xGex alloys at temperatures of 450–500°C and pressures of 30–40 MPa. The resulting Si1-xGexO2 samples were annealed in forming gas (85/15:N2/H2) and the precipitation and growth of Ge crystallites as a function of oxidation and annealing conditions were investigated using FTIR, Raman spectroscopy, XPS, AFM and high resolution SEM. The particle size distribution through the oxide thickness is accounted for by consideration of the incorporation of hydroxyl groups in the amorphous oxide network and their effect on the rate of diffusion of Ge in the amorphous structure during H2 annealing.

SSZ-82 (SEW) is a 12 × 10 membered ring zeolite that offers intriguing catalytic possibilities due to the intersection of pore channels of differing dimensions. Previously, SSZ-82 was a zeolite that could only be directly made as a borosilicate. Here, we show that the borosilicate material can be used as seeds to synthesize an aluminosilicate product. Aluminum-containing SSZ-82 (Al-SSZ-82) was directly synthesized using an interzeolite conversion method: FAU zeolite was the parent zeolite, and boron-containing SSZ-82 (B-SSZ-82) was used as seeds. The conversion of FAU to Al-SSZ-82 was monitored with time, and the use of SSZ-82 seeds, organic structure-directing agent, Na + , and total OH − were all shown to be important for successful conversion to SSZ-82. In addition, the surface area and heteroatom of the SSZ-82 seeds played important roles in the conversion rate: calcining the seeds, grinding the seeds down to smaller particles, and using heteroatoms that are less stable all increased the kinetics of the conversion.