We fabricated thin optical layers in aluminum nitride by magnetron sputtering. Using the techniques of integrated optics, we characterized the layers and we determined the electro-optic coefficients of AlN: r13 = 0.67 pm/V and r33 = −0.59 pm/V.

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The thermodynamics of aluminum nitride formation in the AlCl3‐NH3‐H2 and AlBr3‐NH3‐H2 systems have been studied at 1200° and 1400°K. The nature of the condensed phase and the equilibrium gas phase composition have been determined. Aluminum nitride was the only condensed phase formed under the entire range of the gas phase composition investigated. With a gas phase composition in stoichiometric proportions false(PAlX30=PNH30false) , the yield of aluminum nitride decreased rapidly when the halide or ammonia vapor pressure was higher than 10−3 atm. At high hydrogen concentration, the formation of monohalides always reduced the yield of aluminum nitride. Aluminum nitride films have been deposited on various substrates between 500° and 900°C, using an initial composition of the AlBr3‐NH3‐H2 system corresponding to a thermodynamic yield of aluminum nitride higher than 90%. The films have been confirmed to be aluminum nitride by x‐ray diffraction technique and by Rutherford backscattering spectroscopy. The deposition rate has been investigated with respect to the temperature and the gas phase composition. At an aluminum tribromide vapor pressure of 8×10−5 normalatm , the deposition rate of aluminum nitride decreased with increasing deposition temperature. At an aluminum tribromide vapor pressure of 2.3×10−4 normalatm , the deposition rate increased between 500° and 600°C. Above 600°C, the deposition rate decreased with increasing deposition temperature. A mechanism of the deposition process has been proposed.