Thermal effects on the growth by metal organic chemical vapour deposition of TiO2 thin films on (100) GaAs substrates

TiO2 thin films were deposited on (100) GaAs substrates by LP-MOCVD with deposition temperatures (Td) ranking from 450 to 750 °C. The structure of these layers was studied by X-ray diffraction (XRD) and Raman spectroscopy. The growth of the TiO2 anatase phase was observed for Td<600 °C, while the rutile phase was formed at higher temperatures. Beside this, the formation of pyramidal holes in the GaAs substrate during the deposition process was observed by scanning electron microscopy (SEM) for Td>600 °C. Finally, X-ray photoelectron spectrometry (XPS) and secondary ion mass spectroscopy (SIMS) experiments showed the presence of small quantities of Ga and As through the whole film thickness, slightly increasing at the surface of the layers. This result was related to the SEM observations and explained by considering the growth conditions.