Atomic Layer Deposition of Epitaxial and Polycrystalline SnO₂ Films from the SnI₄/O₂ Precursor Combination

Abstract

Thin films of SnO 2 have been successfully deposited by atomic layer deposition (ALD) using the SnI 4 /O 2 precursor combination. Depositions were carried out in the temperature range 400±750 C on SiO 2 /Si(100) and single-crystalline a-Al 2 O 3 (012) substrates. The films were found to grow as the tetragonal SnO 2 phase (cassiterite), polycrystalline on SiO 2 /Si (100)

CVD of Epitaxial SnO2 Films by the SnI4/O2 Precursor Combination

“…The deposition experiments were performed in a reactor designed for ALD, which has been described in more detail elsewhere [25]. The ALD reactor was operated in CVD mode by feeding in the precursors simultaneously.…”

“…A reason why the 180 twin often has a reduced intensity compared to the main orientation has earlier been proposed in the case of ALD of SnO 2 . [25] It might be due to the fact that the oxygen atoms are not superimposed in the contact plane between the a-Al 2 O 3 (012) and SnO 2 (101) planes (see Fig. 9a,b) and hence is not as energetically favorable.…”

“…However, both polycrystalline films [21] and crystals [22] have been deposited using this precursor combination. Earlier studies of epitaxial SnO 2 thin films grown by atomic layer deposition (ALD) for gas sensing applications, [23] by the SnCl 4 /H 2 O 2 , [24] and SnI 4 /O 2 processes [25] have shown the power of the iodidebased process in producing high quality epitaxial films with enhanced sensitivity to CO compared to that of films deposited by the chloride process. Here we report the results from epitaxial growth of SnO 2 on a-Al 2 O 3 (012) substrates by a heterogeneous surface reaction between SnI 4 and O 2 , with the emphasis on growth kinetics and epitaxial relationships.…”

Atomic Layer Deposition of Co3O4 Thin Films Using a CoI2/O2 Precursor Combination

“…All films were deposited in an on-site-built, hot-wall, horizontal flow-type ALD reactor that has been described in detail elsewhere [28]. The reactor consists of a 40 mm main quartz tube with two smaller quartz tubes, 20 mm and 25 mm, inserted inside.…”

Atomic Layer Deposition of Ta2O5 Using the TaI5 and O2 Precursor Combination

“…However, Ta 2 O 5 has previously been deposited by CVD using the TaI 5 /O 2 precursor combination. [15] Furthermore, it has been shown that it is possible to grow other metal oxides by ALD from metal iodides in combination with O 2 , for example TiO 2 , [16] SnO 2 , [17] and HfO 2 . [18] Very low levels of iodine contamination were reported when the metal iodides were employed, whereas when chloride precursors were used, significantly higher levels of chlorine contamination have been observed.…”