Growth of highly oriented TiO2 thin films on InP(100) substrates by metalorganic chemical vapor deposition

We have studied the growth of highly oriented titanium dioxide (TiO2) thin films on InP(100) substrates at low-temperature by metalorganic chemical vapor deposition (MOCVD), The TiO2 thin films were deposited at a substrate temperature between 300 and 450 degrees C with a different supply ratio of oxygen to the titanium organometallic source of titanium isopropoxide. X-ray diffraction patterns showed the formation of the highly oriented rutile phase with the [110] direction perpendicular to the InP(100) substrate for films grown at a temperature above 350 degrees C, while the sample grown at 300 degrees C indicated a mixed structure with anatase (101) and (200) and rutile (211) and (220) peaks. Scanning electron microscopy (SEM) for the films grown at temperatures above 350 degrees C showed a highly oriented, dense columnar structure. It was suggested that the molar ratio of oxygen gas to the organometallic Ti source is an important parameter to obtain rutile phase TiO2 films at low growth temperature by low temperature MOCVD. From capacitance-voltage and current-voltage measurements of the Al/TiO2/n-InP structure, the dielectric constant was approximately about 90 with a good rectification behavior and low reverse leakage current.