Reynaldo Martínez Guerrero and J. Roberto Vargas García, National Polytechnic Institute, Dept. of Metallurgical Engineering, A.P. 75-874, México 07300, D. F., MEXICO.

Aluminum nitride (AlN) films were prepared on amorphous quartz substrates by chemical vapor deposition (CVD) using an horizontal hot-wall type reactor, (CH₃)₃Al precursor, NH₃ gas as a source of nitrogen and H₂ as the carrier gas. AlN films of different crystalline quality can be obtained at T_dep=700-750°C, P_tot=15 torr, under a H₂ atmosphere. 2 m m-thick AlN films can be grown highly oriented in the [210] direction, whereas, thicker AlN films grow with random orientation. The AlN films were transparent and their refractive indexes were about 1.4-1.9. The low values of the refractive indexes might be attributed to impurity carbon arising from the decomposition of (CH₃)₃Al precursor. By increasing deposition temperature the electrical resistivity of AlN films decreases.