Effect of Composition, Interface, and Deposition Sequence on Electrical Properties of Nanolayered Ta(2)O(5)-Al(2)O(3) Films Grown on Silicon by Atomic Layer Deposition

Nanolayered Ta(2)O(5)-Al(2)O(3) composite films were grown on n-type silicon by atomic layer deposition (ALD) within the overlapped ALD window of 220–270 °C. Moreover, post-annealing treatment was carried out to eliminate defects and improve film quality. Nanolayered Ta(2)O(5)-Al(2)O(3) composite films remain amorphous after 700 °C annealing. The effects of composition, interface, and deposition sequence on electrical properties of Ta(2)O(5)-Al(2)O(3) composite films were investigated in detail utilizing MIS devices. The results demonstrate that the formation of Ta(2)O(5)-Al(2)O(3) composite films by mixing Al(2)O(3) into Ta(2)O(5) can decrease the leakage current effectively, but it leads to the decrease of the dielectric constant and the enhancement of the hysteresis effect. The interfaces in composite films are not conducive to prevent the leakage current. The deposition sequence of Si/(Al(2)O(3)/Ta(2)O(5))(n), Al(2)O(3) as the first covering layer, reduces the leakage current and the hysteresis effect effectively. Therefore, the electrical properties of Ta(2)O(5)-Al(2)O(3) composite films could be regulated by adjusting components and structures via ALD to acquire relatively great dielectric constants and acceptable leakage currents.