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Journal Article 
Indium diffusion and native oxide removal during the ALD of TiO2 films on InAs(100) surfaces 
Ye, L; Gougousi, T 
In Press 
ACS Applied Materials & Interfaces
ISSN: 1944-8244
EISSN: 1944-8252 
A thermal ALD process with tetrakis dimethyl amino titanium and H2O as reagents has been used to deposit TiO2 films on native oxide and etched InAs(100) surfaces at 200°C. TiO2 was deposited on etched InAs(100) surface without the formation of undesirable interfacial layers. X-ray photoelectron spectroscopy data on a series of films of increasing thickness deposited on surfaces covered with native oxide has shown that the surface arsenic oxides are removed within the first 2-3 nm of film deposition. The indium oxides however after an initial reduction seem to persist and increase in intensity with film thickness. For a 6.4 nm TiO2 film, x-ray photoelectron spectroscopy depth profile data demonstrate accumulation of indium oxides at the TiO2 film surface. When the topmost layer of the indium/TiO2 film is removed then a sharp interface between the TiO2 film and the InAs substrate is detected. This observation demonstrates that the surface oxides diffuse through fairly thick TiO2 films and may subsequently be removed by reaction with the precursor and amine by products of the ALD reaction. These finding underscore the importance of diffusion in understanding the so called "interface clean-up" reaction and its potential impact on the fabrication of high quality InAs and other III-V based MOS devices. 
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