Area Selective Growth of Titanium Diselenide Thin Films into Micropatterned Substrates by Low-Pressure Chemical Vapor Deposition

Abstract

The neutral, distorted octahedral complex [TiCl4(SenBu2)2] (1), prepared from the reaction of TiCl4 with the neutral SenBu2 in a 1:2 ratio and characterized by IR and multinuclear (1H, 13C{1H}, 77Se{1H}) NMR spectroscopy and microanalysis, serves as an efficient single-source precursor for low-pressure chemical vapor deposition (LPCVD) of titanium diselenide, TiSe2, films onto SiO2 and TiN substrates. X-ray diffraction patterns on the deposited films are consistent with single-phase, hexagonal 1T-TiSe2 (P3̅m1), with evidence of some preferred orientation of the crystallites in thicker films. The composition and structural morphology was confirmed by scanning electron microscopy (SEM), energy dispersive X-ray, and Raman spectroscopy. SEM imaging shows hexagonal plate crystallites growing perpendicular to the substrate, but these tend to align parallel to the surface when the quantity of reagent is reduced. The resistivity of the crystalline TiSe2 films is 3.36 ± 0.05 × 10–3 Ω·cm with a carrier density of 1 × 1022 cm–3. Very highly selective film growth from the reagent was observed onto photolithographically patterned substrates, with film growth strongly preferred onto the conducting TiN surfaces of SiO2/TiN patterned substrates. TiSe2 is selectively deposited within the smallest 2 μm diameter TiN holes of the patterned TiN/SiO2 substrates. The variation in crystallite size with different diameter holes is determined by microfocus X-ray diffraction and SEM, revealing that the dimensions increase with the hole size, but that the thickness of the crystals stops increasing above ∼20 μm hole size, whereas their lengths/widths continue to increase.

Chemical vapour deposition of antimony chalcogenides with positional and orientational control: precursor design and substrate selectivity

“…Using patterned substrates has previously allowed substrate selective CVD of patterned arrays of a number of metal chalcogenides using chalcogenoether coordination complexes of metal halides as single source precursors. [19][20][21] When MeSb(Te n Bu) 2 is used in CVD in conjunction with patterned substrates, highly selective deposition is observed for substrates in zone (a). SEM images show that deposition occurs exclusively onto the exposed TiN areas of the substrates, with the silica surface remaining bare (Fig.…”

Chemical tuning of electrical transport inTi1−xPtxSe2−y

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Nanoscale arrays of antimony telluride single crystals by selective chemical vapor deposition

“…Position-controlled synthesis of single-crystal chalcogenides nanoplate arrays on mica substrates has also been reported using van der Waals epitaxy 25 26 . We recently showed the selective CVD of a range of binary chalcogenides, including Sb 2 Te 3 , using single source precursors 27 28 29 30 31 . The ability to deposit alloys using single source reagents can be advantageous as it can offer improved control of stoichiometry and fewer defects, while the single source precursors themselves are often less toxic and easier to handle compared to those used in dual source CVD.…”