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

ABSTRACT: The neutral, distorted octahedral complex [TiCl₄(Se ⁿ Bu₂)₂] (1), prepared from the reaction of TiCl₄ with the neutral Se ⁿ Bu₂ 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 (P3?m1), 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 ?·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 ?m 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 ?m hole size, whereas their lengths/widths continue to increase.

SUBMITTER: Benjamin SL 

PROVIDER: S-EPMC3903341 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature