Growth of AlN Films by Hot-Wall CVD and Sublimation Techniques: Effect of Growth Cell Pressure

Abstract

Aluminum nitride (AlN) films were grown on off-axis, Si-terminated 4H-SiC substrates by hot-wall CVD and sublimation techniques. The films were investigated by Infrared reflectance, Optical microscopy, Energy Dispersive X-ray analysis and Cathodoluminescence in a Scanning Electron Microscope with respect to their thickness, morphological, compositional and luminescence properties, in order to examine the influence of the growth cell pressure in either of the two deposition methods. Good quality thick AlN films were obtained by hot-wall CVD at temperature of 1200degreesC and reduced pressure of 100 mbar as reflected in the near stoichiometric N/Al ratio in these layers and in the appearance of the characteristic AlN near band edge emission. The AlN sublimation grown films at temperature of 2100degreesC suffered from island growth irrespective of the background pressure. The supersaturation conditions that affect strongly the growth mode became more favorable when the temperature was reduced to 1900degreesC.