Structure and crystal growth of undoped, as-deposited, and annealed silicon films prepared by chemical vapor deposition (CVD) and low-pressure chemical vapor deposition (LPCVD) of silane have been studied with use of x-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The grain size and a complete texture analysis are performed on CVD films grown at atmospheric pressure and temperature range 600≤Td≤805 °C, LPCVD films grown in the pressure range 0.1≤Pd≤2 Torr and temperature range 500≤Td≤650 °C and annealed amorphous CVD and LPCVD films near Ta=600 °C. We obtain systematically amorphous, strong 〈220〉 polycrystalline, and inhomogeneous partially crystallized films 〈111〉 or 〈311〉 oriented depending on the deposition conditions. The presence of a given texture is explained by a model which takes into account the specific free surface energies of the starting equilibrium forms and the extinction of some crystalline planes by {111} slow growing facets. The appearance of the 〈220〉 texture is explained by a gas phase nucleation of crystal occurring during deposition, whereas the observed 〈311〉 texture of LPCVD films is supposed to be due to a gas-phase nucleation mechanism occurring during the first stages of deposition followed by a solid-phase crystallization mechanism.

The etch rate of 4H–SiC in a SF6 helicon plasma has been investigated as a function of pressure, power injected in the source, substrate bias voltage, and distance between the substrate holder and the helicon source. The highest etch rate yet reported of 1.35 μm/min along with good uniformity on 2 in. SiC substrates was achieved when this distance was minimum. Smooth etched surfaces free of micromasking have been obtained when using a nickel mask and the selectivity SiC/Ni was found to be about 50 under high etch rate conditions. Via holes have been etched to a depth of 330 μm in 4H–SiC substrates.

In the field of industrial hygiene, besides the necessity of monitoring phosphine with direct reading apparatus to prevent accidents, there is a need for a method of sampling and analysing phosphine to control workers' exposure. The use of filters impregnated with silver nitrate to collect arsine, phosphine and stibine in workplace air has been described in the literature. Having previously chosen this type of filter to collect arsine, we studied its characteristics for phosphine capture. A filter impregnated with sodium carbonate was used both as a prefilter to collect the particles and to trap arsenic trioxide. After dissolving the silver compounds in nitric acid, ICP emission spectrometry was used to carry out the analysis. This article describes the comparative sampling we performed in a microelectronic laboratory and in a fumigation chamber (130 samples) to determine the concentration of AgNO3 impregnation solution to be used, the detection limit of the method and the retention capacity of the impregnated filters. Interference with other gases reacting with silver nitrate was studied and the storage time for sampled filters and analysis solutions was checked. The detection limit of the adopted method is better than 1 microg per filter, and the retention capacity exceeds 300 microg per filter. The problem of how to sample phosphine when H2S, NH3, or HCl is present has been solved, but the problem of sampling phosphine in atmospheres where acetylene evolves remains. Sampled filters and filter solutions are stable for more than three months at ambient temperature.

Aims-A prospective study was carried out in order to evaluate the eYcacy and safety of peribulbar anaesthesia during keratoplasty and to describe surgical conditions. Methods-Of 137 consecutive keratoplasties, 100 (73%) were performed under peribulbar anaesthesia. Patients received a mean volume of 16.5 (SD 4) ml (range 9-22 ml) of a mixture of etidocaine, bupivacaine, and hyaluronidase. Ocular compression duration was at least 20 minutes and intraocular pressure (IOP) was measured with a Tonopen after injection, compression, and before trephination. Degree of akinesia, pain scoring, complications, and surgical conditions were studied. Results-Before trephination, IOP was 5.73 mm Hg below the preinjection value and was never above 21 mm Hg. Akinesia was complete in 80% of cases and 94% of patients found that surgery was painless. Two patients (2%) were very agitated during surgery. The last patient presented with an acute intraoperative suprachoroidal haemorrhage that did not result in a true expulsive haemorrhage despite an "open sky" situation. Surgical conditions were judged to be optimal by the patients in 92% of cases and by the surgeon in 98% of cases. Conclusion-These results demonstrate that peribulbar anaesthesia oVers excellent anaesthesia and akinesia during keratoplasty and may be recommended for this type of surgery. (Br J Ophthalmol 1999;83:104-109)

Low-temperature deposition (room temperature, RT-250 °C) of high-resistivity SiO2 layers has been successfully developed on InP substrates. Complete electrical characteristics of metal-insulator-semiconductor (MIS) diodes show promising characteristics in terms of barrier height at the SiO2-InP interface and in terms of interface state distribution (NSS). Leakage current is essentially bulk limited (ρ=4×1015 Ω cm) until a high electrical field in the range 4–6 MV cm−1 and a minimum value of NSS of 2×1011 cm−2 eV−1 range is achieved, without particular surface treatment. These results show that the technique is well adapted to n-type depletion-mode MIS field-effect transistor processing.