SURFACE X-RAY-ABSORPTION FINE-STRUCTURES OF SIOX (O-LESS-THAN X LESS-THAN-2) AND SINX (0-LESS-THAN X LESS-THAN-4/3) PRODUCED BY LOW-ENERGY ION-IMPLANTATION IN SI(100)

X-ray-absorption near-edge structures (XANES) have been investigated for silicon oxide and nitride with nonstoichiometric compositions (SiO(x)SiN(x) produced by low-energy ion implantation in Si(100). The XANES structures at the Si 2p edge for SiO(x) at x greater-than-or-equal-to 0.2 resemble those reported for SiO2, and those at the O 1s edge are independent of the x value. These observations indicate that the conduction band of SiO(x) is mainly composed of the orbitals of SiO2. On the other hand, the XANES structures of SiN(x) change with the x value, and the sharp resonance corresponding to a N dangling bond was observed at the N 1s edge for x > 1.0. These findings suggest that in the SiN(x) phase there is a random-bonding structure rather than a mixture of Si and Si3N4 islands.