Composition-Dependent Structural and Electronic Properties of α-(Si1−x C x )3N4

• Published in: Journal of physical chemistry. C Vol. 115; no. 5; pp. 2448 - 2453
• Main Authors: Xu, M, Xu, S, Duan, M. Y, Delanty, M, Jiang, N, Li, H. S, Kwek, L. C, Ostrikov, K
• Format: Journal Article
• Language: English
• Published: American Chemical Society 10-02-2011
• Subjects: C: Electron Transport, Optical and Electronic Devices, Hard Matter
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp110109x

The highly unusual structural and electronic properties of the α-phase of (Si1−x C x )3N4 are determined by density functional theory (DFT) calculations using the Generalized Gradient Approximation (GGA). The electronic properties of α-(Si1−x C x )3N4 are found to be very close to those of α-C3N4. The bandgap of α-(Si1−x C x )3N4 significantly decreases as C atoms are substituted by Si atoms (in most cases, smaller than that of either α-Si3N4 or α-C3N4) and attains a minimum when the ratio of C to Si is close to 2. On the other hand, the bulk modulus of α-(Si1−x C x )3N4 is found to be closer to that of α-Si3N4 than of α-C3N4. Plasma-assisted synthesis experiments of CN x and SiCN films are performed to verify the accuracy of the DFT calculations. TEM measurements confirm the calculated lattice constants, and FT-IR/XPS analysis confirms the formation and lengths of C−N and Si−N bonds. The results of DFT calculations are also in a remarkable agreement with the experiments of other authors.