The effect of solvent on the morphology of indium oxide deposited by aerosol-assisted chemical vapour deposition

Aerosol-assisted chemical vapour deposition (AACVD) reactions of InMe3 and a mono-functional or donor-functional alcohol have been investigated and the resulting film morphology studied using scanning electron microscopy. AACVD of InMe3 and 6 equivalents of the donor-functionalized alcohol HOCH2CH2NMe2 in toluene resulted in the deposition of transparent indium oxide films, with a slight brown tinge, at 450°C. In contrast, AACVD of InMe3 and 6 equivalents of MeOH in toluene resulted in no film growth. However, use of methanol as both the solvent and oxygen source via AACVD of InMe3 in MeOH at a range of temperatures (350–500°C) afforded crystalline transparent indium oxide films. Similarly, AACVD of InMe3 and 6 equivalents of HOCH2CH2NMe2 in MeOH resulted in transparent indium oxide films with better substrate coverage. The indium oxide films were analyzed by a range of techniques including scanning electron microscopy, glancing-angle X-ray powder diffraction, UV-visible spectroscopy, and wavelength dispersive analysis of X-rays, which confirmed the formation of cubic In2O3 with band-gaps in the range 3.51–3.60 eV. Scanning electron microscopy showed a variation in film morphology and indicated that both temperature and the use of methanol influenced the resulting microstructure. Sheet resistance and Hall effect measurements indicate that the films deposited at 450°C are suitable candidates for transparent conducting oxide materials.