Vapor deposition of copper(I) bromide films via a two-step conversion process

Abstract

Thin films of Cu 2 S grown by pulsed-chemical vapor deposition of bis(N,N'-di-secbutylacetamidinato)dicopper(I) and hydrogen sulfide were converted to CuBr upon exposure to anhydrous hydrogen bromide. X-ray diffraction shows that the as-deposited films have a polycrystalline Cu 2 S structure. After exposure to HBr gas, the surface of the films is transformed to a γ-CuBr polycrystalline structure. Scanning electron microscopy and X-ray photoelectron spectroscopy reveal complete conversion of up to 100 nm of film. However, when the conversion to CuBr approaches the interface between as-2 deposited Cu 2 S and the SiO 2 substrate, the morphology of the film changes from continuous and nanocrystalline to sparse and microcrystalline.

Vapor Deposition of Transparent, p-Type Cuprous Iodide Via a Two-Step Conversion Process

“…Furthermore, we have improved upon our previous methodology. In the CuBr work, 42 we noted some difficulty in controlling the film morphology, consistent with the broader literature on cuprous halides. 6 Here, we addressed this challenge by balancing the relative rates of nucleation and growth of CuI.…”

“…As an alternative to direct CVD of CuI, we envisioned the two-step conversion of Cu (2– x ) S films to CuI upon exposure to HI, analogous to our recent finding that CVD Cu (2– x ) S films may be exposed to HBr to afford CuBr . Despite the obvious concern that the larger radius of iodide than bromide would inhibit the exchange reaction, we have found this reaction affords CuI rapidly, with conversion rates greater than 4.5 nm/min observed at room temperature and atmospheric pressure.…”

“…2.1. CVD Growth of Cu (2−x) S and Cu 2 O. Cu (2−x) S was deposited by a pulsed-CVD literature process 42,43 in a custom-built, hot-walled ALD reactor that has been described previously. 44 Thin films of Cu 2 O were deposited by standard CVD in a custom-built, hot-walled reactor described in detail elsewhere.…”

“…Unfortunately, this reaction is complicated by the same issues that impede the direct vapor deposition of CuBr. 42 Specifically, within the CVD reaction sequence the acetamidine ligand is released while in the presence of HI, yielding the nonvolatile acetamidinium iodide salt by a rapid acid−base reaction. Our exploratory studies indicate that direct CVD of CuI using [Cu(sBu 2 AMD)] 2 and HI, generated by the thermal decomposition of tert-butyl iodide at 500 °C, produces films that are carbon-and nitrogen-contaminated over a range of deposition temperatures.…”

“…One plausible route to a thin film of CuI via CVD would be the reaction between the well-understood and commercially available bis­( N , N′ -di- sec -butylacetamidinato)­dicopper­(I), [Cu­( s Bu 2 AMD)] 2 , and anhydrous hydrogen iodide. Unfortunately, this reaction is complicated by the same issues that impede the direct vapor deposition of CuBr . Specifically, within the CVD reaction sequence the acetamidine ligand is released while in the presence of HI, yielding the nonvolatile acetamidinium iodide salt by a rapid acid–base reaction.…”