Abstract
Abstract : Pyrolytic aluminum nitride has been deposited on refractory electrical conductors using AlCl3.NH3 as the source material. Effects which pressure, temperature and rate of deposition have on electrical and other properties of deposits have been determined. Density of deposited coatings approach that of the calculated value. However, they still contain residual chlorine, causing electrical properties to fall short of what is expected of dense high purity AlN. Pyrolytic silicon nitride has been prepared from gaseous mixtures of silane and ammonia under varying conditions of temperature and pressure. Adherent, relatively soft, amorphous films have been deposited on substrates heated in the 700 to 800 C range while hard crystalline coatings of Alpha-Si3N4 have been obtained in the vicinity of 1250C. Coatings, which are both hard and amorphous, have been deposited at 1000C and have been characterized by a number of techniques. High temperature dielectric property tests of aluminum and silicon nitrides have indicated good high temperature resistivities with some samples, but considerable variability existed among samples. Measurements on aluminum nitride in particular, have indicated the presence of impurity conduction. Silicon nitride coatings seem to demonstrate more consistently high resistivities which make this material a potentially useful dielectric at 800 to 1000C at low voltages.
Published Version
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