Effect of temperature on carbon nitride films synthesized by ion-beam-assisted pulsed laser deposition

Carbon nitride thin films were deposited by pulsed laser deposition with ni trogen ion beam assistance at a substrate temperature varying from room tem perature to 800 degreesC. The effect of the substrate temperature on the ni trogen content, surface morphology, structure, and electrical property of t he carbon nitride films was investigated. The deposited films were characte rized by atomic force microscopy (AFM), Fourier transform infrared (FTIR) s pectroscopy, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, an d four-probe resistance. The nitrogen content of the deposited films reache d its maximum value of 25% at a substrate temperature of 400 degreesC. AFM images revealed that an island structure occurred and developed on the surf ace of the films deposited at the high substrate temperature. FTIR and XPS spectra showed the existence of sp(3)C-N and sp(2)C=N bonds in the deposite d films. The deposited carbon nitride films had an amorphous structure with two carbon nitride phases inclusions, which had a stoichiometry near C3N4 and a variable stoichiometry from C5N to C2N, respectively. With the increa se in substrate temperature, the relative content of the sp(3)C-N bonds, i. e., the C3N4 phase, increased and the crystallization degree of the deposit ed films enhanced, which were confirmed by the Raman analysis. Very few C=N bonds in the films were found as compared to other carbon-nitrogen bonds. Electrical resistivity exhibited the highest value for the film deposited a t 400 degreesC. Investigation results indicated that the high substrate tem perature could promote the formation of C3N4 phase. (C) 2000 American Insti tute of Physics. [S0021-8979(01)03601-5].