John Waters

Growth of lead chalcogenide thin films using single-source precursors

A series of lead dithiocarbamato complexes, [Pb(S2CNRR′)2] (R = Me, Et; R′ = iPr, nBu) and dichalcogenoimidodiphoshanto complexes, [Pb((EPiPr2)2N)2] (E = S, Se) have been synthesised and characterised. These compounds have been employed as single-source precursors for the growth of lead chalcogenide thin films by aerosol-assisted chemical vapour deposition (AACVD) and low-pressure metal–organic chemical vapour deposition (LP-MOCVD) on glass substrates. X-Ray powder diffraction (XRPD) studies show that the films are composed of cubic PbS/Se. The solid-state structures of the symmetrically substituted complexes, [Pb(S2CNR2)2] (R = C6H10, C5H11), have been determined by single-crystal X-ray crystallography.

The deposition of thin films of CuME2 by CVD techniques (M = In, Ga and E = S, Se)

Thin film(s) of chalcopyrite CuME2 (where M = In or Ga; E = S or Se) have been grown by low-pressure metal-organic chemical vapour deposition (LP-MOCVD) or aerosol-assisted chemical vapour deposition (AACVD) using the precursors M(E2CNMenHex)3 and Cu(E2CNMenHex)2. Films were grown on various substrates between 350–500 °C and characterized by X-ray diffraction, XPS, optical spectroscopy (UV/Vis), EDAX and scanning electron microscopy.

Ligand influence on the formation of P/Se semiconductor materials from metal–organic complexes

The complexes [Ni{(SeP(i)Pr(2))(2)N}(2)] (2), [Ni(Se(2)P(i)Pr(2))(2)] (), and [Co(Se(2)P(i)Pr(2))(2)] (4) were synthesised and the X-ray single crystal structures of (1) and (2) were determined. Thin films of nickel selenide, cobalt selenide and cobalt phosphide have been deposited by the chemical vapour deposition method using imidodiselenophosphinato-nickel(ii) (1), -cobalt(ii) [Co{(SeP(i)Pr(2))(2)N}(2)] (3), diselenophosphinato-nickel(ii) (2), -cobalt(ii) (4) and diselenocarbamato-nickel(ii) [Ni(Se(2)CNEt(2))(2)] (5), and -cobalt(iii) [Co(Se(2)CNEt(2))(3)] (6) precursors.

Aerosol-assisted metallo-organic chemical vapour deposition of Bi2Se3 films using single-molecule precursors. The crystal structure of bismuth(III) dibutyldiselenocarbamate

The complexes [Bi{Se2CN(C2H5)2}3], [Bi{Se2CN(C4H9)2}3], [Bi{Se2CN(CH3)(C4H9)}3] and [Bi{Se2CN(CH3)(C6H13)}3] have been synthesized and characterized structurally using IR, 1H and 13C NMR. In addition, the crystal structure of [Bi{Se2CN(C4H9)2}3] was determined by single-crystal X-ray diffraction, showing the bismuth centre coordinated to three dialkyldiselenocarbamate ligands through the selenium donor atoms. The Bi(III) compounds were used as precursors for the deposition of Bi2Se3 films on glass substrates through aerosol-assisted metallo-organic chemical vapour deposition (AA-MOCVD).

Fabrication of thin films of bismuth selenide using novel single-source precursors by metal organic chemical vapor deposition

A metal-organic compound, Bi[(SePiPr2)2N]3 has been synthesized and used as a single-source precursor for the deposition of bismuth selenide thin films via low-pressure metal-organic chemical vapor deposition. Crystalline thin films of rhombohedral Bi2Se3 have been deposited on glass substrates. The films have been characterized by X-ray powder diffraction, scanning electron microscopy and energy dispersive analysis of X-rays.

Factors controlling material deposition in the CVD of nickel sulfides, selenides or phosphides from dichalcogenoimidodiphosphinato complexes: deposition, spectroscopic and computational studies.

The series of nickel dichalcogenoimidodiphosphinates [Ni{(i)Pr(2)P(X1)NP(X2)(i)Pr(2)}(2)]: X1 = S, X2 = Se (1), X1 = X2 = S (2), and X1 = X2 = Se (3) have been successfully used as single-source precursors (SSPs) to deposit thin films of nickel sulfide, selenide or phosphide; the material deposited depended on both temperature and method used for the deposition. Aerosol-assisted (AA) chemical vapour deposition (CVD) and low-pressure (LP) CVD were used. The as-deposited films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). A variety of phases including: Ni(2)P, Ni(0.85)Se and NiS(1.03) were deposited under different conditions. The mechanism of decomposition to the phosphide, selenide, or sulfide was studied by pyrolysis gas chromatography mass spectrometry (Py-GC-MS) and modelled by density functional theory (DFT).

Investigations on the trigonal twist process in the pseudooctahedral complexes [MX(CO)2(PP)(η3-R)] (M=Mo or W; X=halide or pseudohalide; PP=bidentate P-donor ligand; R=cycloheptatrienyl, cyclohexenyl or cyclooctenyl)

Abstract A series of complexes [MX(CO) 2 (PP)(η 3 -R)] [M=Mo or W; X=halide, NCO or NCS; PP=Ph 2 P(CH 2 ) n PPh 2 ( n =1−3)] have been prepared. Variable temperature 31 P{ 1 H}-NMR investigations reveal the operation of a trigonal twist fluxional process in complexes where R=cycloheptatrienyl (C 7 H 7 ), cyclohexenyl (C 6 H 9 ) or cyclooctenyl (C 8 H 13 ) with Δ G C ‡ (the free energy of activation at the temperature of coalescence) strongly R-dependent. Using the cycloheptatrienyl complexes [MX(CO) 2 {Ph 2 P(CH 2 ) n PPh 2 }(η 3 -C 7 H 7 )] detailed investigations have been made to establish the effect on Δ G C ‡ of variation of X , n and M.

Imino-bis(diisopropylphosphine chalcogenide) complexes of arsenic, antimony and bismuth. Synthesis, CVD studies and X-ray structure of M[N(EPiPr2)2]n(E = Se, S; M = As, Sb, Bi)

Bismuth, and antimony complexes of imino-bis(diisopropylphosphine chalcogenide) ligands, M[N(EPiPr2)2]n (E = S or Se; M = Bi and Sb) have been prepared by the reaction of the sodium salt of NH(EPiPr2)2 (E = S or Se) with the appropriate group 15 metal salt in methanol. The complexes are monomeric in the solid state and air stable. The crystal structures of Bi[(iPr2PS)2N]3 and Sb[(iPr2PS)2N]3 have been determined by X-ray diffraction. The compounds are isostructural, with distorted octahedral coordination geometries and extended P–Se bonds. The bismuth compounds have been used in both AA-MOCVD and LP-MOCVD to deposit thin films of bismuth chalcogenide.