Epitaxial Growth of Silicon by Vacuum Sublimation
SINGLE crystal layers of silicon up to several μ thick have been deposited on to a heated single crystal silicon substrate from a sublimating source. We believe we can grow good epitaxial crystals at a lower growing temperature than previous experiments1 by reducing the growth rate in a good vacuum free from contamination.
Low Voltage Electron Diffraction Study of the Oxidation and Reduction of Silicon
Low voltage electron diffraction and pumping speed measurements have been used to study the reactions of oxygen with clean Si (111) and (100) surfaces in the temperature range between 600° and 1000°C and the oxygen pressure range between 7×10−9 and 1×10−4 mm Hg. The results support the contention that a wide region in which Si is atomically clean exists in this range. Measurements of steady states yield an activation energy of about 90 kcal/mol for the clean‐up process. The results also suggest a practical method for producing pure coatings of SiO2 by a technique similar to, but with several advantages over, the familiar Si+SiO2 reaction process.
PULSE: a high-repetition-rate linac driver for x-ray FELs
We describe a staged concept for a linac-based freeelectron laser providing coherent tuneable VUV and soft X-ray output with pulse lengths down to 10 fs or less. Use of 1.3 GHz cryomodules operated with CW RF will allow flexible pulse patterns at potentially very high repetition rates up to 1 MHz. We consider the options for FELs that may be included in a facility of this type.