In-situ X-ray Photoemission Spectroscopy Study of Atomic Layer Deposition of TiO₂ on Silicon Substrate

Abstract

In-situ X-ray photoemission spectroscopy (XPS) has been used to investigate the initial stages of TiO2 growth on a Si(001) substrate by atomic layer deposition (ALD). The core level spectra of Si 2p, C 1s, O 1s, and Ti 2p were measured at every half reaction in the titanium tetra-isopropoxide (TTIP)–H2O ALD process. The ligand exchange reactions were verified using the periodic oscillation of the C 1s concentration, as well as changes in the hydroxyl concentration. XPS analysis revealed that Ti2O3 and Si oxide were formed at the initial stages of TiO2 growth. A stoichiometric TiO2 layer was dominantly formed after two cycles and was chemically saturated after four cycles.

Quantifying the Extent of Ligand Incorporation and the Effect on Properties of TiO2 Thin Films Grown by Atomic Layer Deposition Using an Alkoxide or an Alkylamide

“…In both cases, TTIP ligands would be trapped in the film during the deposition process and then removed during the thermal treatment. The ligand insertion has already been observed during an in situ XPS investigation 42,43 and by in situ surface-enhanced Raman spectroscopy (SERS). 44 However, here we give the first evidence of ligand removal after thermal treatment.…”

“…that have been apparently incorporated into the TiO 2 film as reported earlier. 43,53 Since very similar results are obtained for TTIP-An and TDMAT-AG, one has to investigate the O 1s region of the three types of layers to compare the amount of ligands that are possibly trapped during the ALD process. Figures 6d, 6e bands at 1110 and 1170 cm −1 correspond respectively to the C-O symmetric and antisymmetric stretching modes in the isopropoxide ligand, 19,54 while the weak absorptions of the C-H bending modes from the alkyl chain are detected between 1380 and 1500 cm −1 .…”

Low-Temperature Atomic Layer Deposition of Metal Oxide Layers for Perovskite Solar Cells with High Efficiency and Stability under Harsh Environmental Conditions

“…Perovskites films with TiO 2 O−Ti bond, which increased with increasing ALD cycles. 44 It illustrated that the deposited TDMAT had reacted with H 2 O and other oxygen-containing groups adsorbed onto the perovskite layer and formed a TiO 2 thin layer, and also TiO 2 is the main product after 40 ALD cycles. The chemical composition of titanium oxide was further analyzed by XPS images of Ti 2p 3/2 (Figure S8).…”

Electrical and optical properties of TiO2 thin films prepared by plasma‐enhanced atomic layer deposition

“…The Ti 2p peak (of the as‐introduced TiO 2 film) is composed of spin doublets Ti 2p 3/2 and Ti 2p 1/2 . The Ti 2p 3/2 and Ti 2p 1/2 peaks are centred at binding energy value of 458.8 and 464.8 eV respectively, and the separation between the Ti 2p 3/2 and the Ti 2p 1/2 peaks is 5.8 eV, which correspond to TiO 2 .…”