Structural and electrical properties of AlN layers grown on silicon by reactive RF magnetron sputtering

Abstract

AlN films of different thicknesses were deposited on n-Si (100) substrates by reactive radio frequency (rf) magnetron sputtering. Dependences of structure and electrical properties on thickness of deposited films were researched. The structures of the films were analyzed with scanning electron microscopy (SEM) and with transmitting electron microscopy (TEM). Electrical properties of the films were investigated on Au-AlN-(n-Si) structures by means of current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) techniques. Electron microscopy investigations had shown that structure and chemical composition of the films were thickness stratified. Near silicon surface layer was amorphous aluminum oxide one contained traps of positive charges with concentration of about 4 × 1018 cm−3. Upper layers were nanocrystalline ones consisted of both wurzite AlN and cubic AlON nanocrystals. They contained traps both positive and negative charges which were situated within 30 nm distance from silicon surface. Surface densities of these traps were about 1012 cm−2. Electron traps with activation energies of (0.2 ÷ 0.4) eV and densities of about 1010 cm−2 were revealed on interface between aluminum oxide layer and silicon substrate. Their densities varied weakly with the film thickness.