Growth of Bi₂O₃ Ultrathin Films by Atomic Layer Deposition

Abstract

Bismuth trioxide (Bi 2 O 3 ) ultrathin films were successfully synthesized on silicon substrates by means of atomic layer deposition (ALD) using Bi(thd) 3 (thd: 2,2,6,6-tetramethyl-3,5heptanedionato) and H 2 O as precursors. The optimum ALD window was about 270−300 °C, and an ALD-type growth mechanism via surface saturation reaction was identified; the growth rate was about 0.1 Å/cycle. The X-ray diffraction and high-resolution transmission electron microscopy investigation revealed that Bi 2 O 3 films crystallized into a predominant alpha phase above 250 °C. The resistivity at room temperature was about 1.2 × 10 6 Ω•cm, which is also proof of the α-phase of as-deposited Bi 2 O 3 films. In addition, a new method to obtain γ-Bi 2 O 3 film was discovered. The α-Bi 2 O 3 films (synthesized by ALD) transformed into metastable γ-Bi 2 O 3 with preferred orientation (222) after annealing above 512 °C, and γ-phase could persist at room temperature.

Influence of composition on structure, morphology and dielectric properties of BixAlyOz composite films synthesized by atomic layer deposition

“…With further increase of bismuth cycles, a new characteristic peak diffracted in the (012) plane at 2θ≈28 o starts to present in the pattern of m=20 sample. This is one of the main peaks characterizing the α-phase Bi 2 O 3 , 22,23 and the presence of this peak can still be attributed to the change of grain constituent. Due to the smaller number of ALD cycles as in the case of the m=5 sample, the grains show a small size and the grain gaps are evident.…”

“…This was previously discussed by our research group in detail. 22 Likewise, the radicals of Bi(thd) 3 are much larger and complicated compared to those of TMA. Therefore, TMA is considered to be able to diffuse into inner films through the space among various Bi 2 O 3 molecules.…”

Advances in Deposition of Main‐Group Metal Oxides and Rare‐Earth Oxides from Metal Enolates

“…The optimal ALD window was 270-300 ∘ C. The growth rate on silicon was 0.2 and 0.1 Å per cycle at 200 and 300 ∘ C, respectively. Annealing the as-deposited α-bismuth oxide layers at 512 ∘ C gave the metastable γ-Bi 2 O 3 phase as shown in Figure 4 78 [Bi(hfac) 2 (Ph)], prepared by stepwise reaction of BiPh 3 with hfacH, or its solvates [Bi(hfac) 2 (Ph)L] (L = H 2 O, Me 2 CO, thf, DMA, DMSO, PhCN), obtained by recrystallization, underwent thermal decomposition to Bi 2 O 3 in air, or to BiOF under inert conditions 85 . The complex [Bi 4 (hfpt) 2 (hfac) 4 ] (hfpt = 1,1,1,5,5,5-hexafluoropentane-2,2,4,4-tetrolate) was synthesized from BiPh 3 and hfptH 4 in anhydrous coordinating solvents.…”

Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method

“…The reaction mechanism [22] of Bi(thd) 3 and H 2 O can be described with Eqs. (1)-(3): the whole reaction can be described in Eq.…”