A comparative study of the electrical properties of TiO₂films grown by high-pressure reactive sputtering and atomic layer deposition

Abstract

Oxide-semiconductor interface quality of high-pressure reactive sputtered (HPRS) TiO 2 films annealed in O 2 at temperatures ranging from 600 to 900 • C, and atomic layer deposited (ALD) TiO 2 films grown at 225 or 275 • C from TiCl 4 or Ti(OC 2 H 5 ) 4 , and annealed at 750 • C in O 2 , has been studied on silicon substrates. Our attention has been focused on the interfacial state and disordered-induced gap state densities. From our results, HPRS films annealed at 900 • C in oxygen atmosphere exhibit the best characteristics, with D it density being the lowest value measured in this work (5-6 × 10 11 cm −2 eV −1 ), and undetectable conductance transients within our experimental limits. This result can be due to two contributions: the increase of the SiO 2 film thickness and the crystallinity, since in the films annealed at 900 • C rutile is the dominant crystalline phase, as revealed by transmission electron microscopy and infrared spectroscopy. In the case of annealing in the range of 600-800 • C, anatase and rutile phases coexist. Disorder-induced gap state (DIGS) density is greater for 700 • C annealed HPRS films than for 750 • C annealed ALD TiO 2 films, whereas 800 • C annealing offers DIGS density values similar to ALD cases. For ALD films, the studies clearly reveal the dependence of trap densities on the chemical route used.

Anomalous C-V response correlated to relaxation processes in TiO2 thin film based-metal-insulator-metal capacitor: Effect of titanium and oxygen defects

“…3 Its variability is generally explained by the dependence of the permittivity on the crystalline phase, deposition method and process parameters of the TiO 2 . Various techniques such as thermal 4 or anodic oxidation, 5 electron beam evaporation, 6 chemical vapor deposition (CVD), 7 plasma-enhanced chemical vapor deposition, 8 sol-gel methods, 9 reactive sputtering methods, 10,11 and atomic layer deposition (ALD) [12][13][14] have been reported for TiO 2 thin film fabrication. Among them, ALD seems highly suitable for obtaining conformal films with uniform thickness even at low temperatures, 15,16 allowing the manufacturing of insulator films with desired and reproducible properties.…”

“…Such impurities induce additional lattice defects to the common ones, leading to lattice distortion, degradation of crystallinity, and insertion of additional trap states into the dielectric. 12 The reduction or oxidation of Ti ions represents another impurity source. The appearance of different stable oxidation states of Ti such as Ti 3þ and Ti 4þ is commonly observed and these act as electron donors and high leakage paths.…”

Structural, Dielectric and Optical properties of Sputtered TiO2 nano-films

“…When sputter power increased to 120 W, the absorption bands at 494 and 668 were observed with minimum intensity. The band situated at 494 and 668 cm -1 related to the rutile phase vibrational mode of TiO 2 [21]. Further increase of sputtering power to 160 W, the intensity of the bands at 494 and 668 cm -1 were increased indicated the growth of rutile phase TiO 2 .…”

Synthesis, characterization, and photoactivity of InTaO4 and In0.9Ni0.1TaO4 thin films prepared by electron evaporation

“…This behavior is typical of low conductive oxides annealed in oxygen. 19 On the other hand, the dielectric character of the films is confirmed by the analysis of dc their conductivity as a function of temperature. The curves in Fig.…”