SiCx Ny thin films have been deposited by ablating a sintered silicon carbide target in a controlled nitrogen atmosphere. The structural and the optical properties of the films were investigated by x-rayphotoelectron spectroscopy (XPS) and spectroscopic ellipsometry. The nitrogen content was found to be dependent on the nitrogen partial pressure and did not exceed 7.5%. XPS measurements of the N 1s,C1s, and Si 2p photoelectron peaks pointed out the nitrogen preferential bonding to silicon atoms with a concurrent decrease of the SiC and SiSi bond density. A slight increase of sp3 hybridized carbon bonds has been also observed. The optical band gap E g values, obtained from fitting the ellipsometric data with an appropriate multiple layers model, were found to increase up to 2.4 eV starting from a value of 1.6 eV for a non-nitrogenated sample. This finding was related to progressive substitution of the weaker SiSi bonds by the stronger SiC and SiN ones which, presumably, involves the removal of electronic states lying at the band edges.
Bonding configurations and optical band gap for nitrogenated amorphous silicon carbide films prepared by pulsed laser ablation
Trusso S;
2002
Abstract
SiCx Ny thin films have been deposited by ablating a sintered silicon carbide target in a controlled nitrogen atmosphere. The structural and the optical properties of the films were investigated by x-rayphotoelectron spectroscopy (XPS) and spectroscopic ellipsometry. The nitrogen content was found to be dependent on the nitrogen partial pressure and did not exceed 7.5%. XPS measurements of the N 1s,C1s, and Si 2p photoelectron peaks pointed out the nitrogen preferential bonding to silicon atoms with a concurrent decrease of the SiC and SiSi bond density. A slight increase of sp3 hybridized carbon bonds has been also observed. The optical band gap E g values, obtained from fitting the ellipsometric data with an appropriate multiple layers model, were found to increase up to 2.4 eV starting from a value of 1.6 eV for a non-nitrogenated sample. This finding was related to progressive substitution of the weaker SiSi bonds by the stronger SiC and SiN ones which, presumably, involves the removal of electronic states lying at the band edges.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
