Correlation between chemical-bonding states and fixed-charge states of Sr-silicate film on Si(100) substrate

Abstract

The authors studied the correlation between the chemical bonding (CB) states and fixed charge (FC) states of Sr-silicate films grown on Si(100) substrates [Sr-silicate/Si(100)]. The Sr-silicate/Si(100) samples were synthesized by silicate reaction of SrO layers on the Si substrates through the diffusion of Si atoms from the substrates by thermal annealing in oxygen atmosphere. The CB states and the FC states of the Sr-silicate/Si(100) samples were obtained from their O 1s core-level x-ray photoemission spectra and the shift in voltage from the flat band state in their capacitance–voltage curves, respectively. Peak fittings of the O 1s core-level spectra for each sample were carried out with the three components of Si–O, Si–O–Sr, and Sr–O bonds to determine the CB state. The thin Sr-silicate layers were mainly constructed of the Si-O-Sr component. With increasing thickness, the amount of Si-O-Sr component decreased while that of Sr-O increased. The thickness dependency of the FC density showed a good agreement with that of the Si-O-Sr component, revealing a clear correlation between FC and Sr–O–Si bonding. Our results suggest that silicate bonding plays an important role in FC generation in Sr-silicate systems.