Open volume defects in ultra-thin TiO2 layers embedded in VMCO-like samples studied with positron annihilation spectroscopy

Positron annihilation signals from VMCO-like samples grown by atomic layer deposition at different temperatures are utilized for the characterization of differences in open volume defects in TiN/TiO[Formula: see text]/a-Si heterostructures. Doppler and coincidence Doppler mode of positron annihilation spectroscopy combined with a monoenergetic positron beam were used for this study. Differences observed in the Doppler parameters indicate differences in the positron trapping states of the TiO[Formula: see text] epilayers grown at different temperatures. Furthermore, the coincidence-Doppler results show that these differences cannot be due to intermixing of the TiO[Formula: see text] and a-Si layers and formation of thin SiO[Formula: see text] layers at the interface during the growth process. The results indicate that the amount of open volume defects in the TiO[Formula: see text] layer of the VMCO-structure seems to increase with an increase in the growth temperature.