Atomic layer deposition of In2O3 using cyclopentadienyl indium:: A new synthetic route to transparent conducting oxide films

Indium oxide (In2O3) forms the basis for an important class of transparent conducting oxides that see wide use in optoelectronic devices, flat-panel displays, and photovoltaics. Here we present a new method for depositing In2O3 thin films by atomic layer deposition (ALD) using alternating exposures to cyclopentadienyl indium and ozone. Using a precursor vaporization temperature of 40 degrees C and deposition temperatures of 200-450 degrees C, we measure growth rates of 1.3-2.0 angstrom/cycle. A significant advantage of this synthesis route over previous techniques is the ability to conformally coat porous materials such as anodic aluminum oxide membranes. The deposited films are nanocrystalline, cubic phase In2O3 and are highly transparent and conducting. In situ quadrupole mass spectrometry and quartz crystal microbalance measurements elucidate the details of the In2O3 growth mechanism.