The Chemical Vapor Deposition of Nickel Phosphide or Selenide Thin Films from a Single Precursor

Abstract

Nickel phosphide and nickel selenide semiconductors are potential materials for photoelectrochemical solar cells. 1,2 They also have interesting electrical and magnetic properties and have promising applications as catalysts 3 and in sensors. 4 Nickel phosphide is an n-type semiconductor with a band gap of 1.0 eV, whereas the selenide is a p-type with a band gap of 2.0 eV. There are only few reports on the deposition of nickel phosphide films which include by magnetron sputtering, 5 electrodeposition, 6 electroless deposition, 7 or the reaction of orthophosphoric acid on a nickel substrate. 1 Nickel selenide films were prepared by electrodeposition, 2 solution growth, 8 reactive diffusion, 9 or chemical vapor deposition (CVD) methods. 10 As far as we know there is no report on the deposition of a Ni 0.85 Se/Ni 2 P heterostructure. Single source precursor (SSP) chemistry has attracted considerable interest for the growth of semiconductor thin films and nanoparticles. 11 Herein we report the synthesis and characterization of imido-bis-(diisopropylthioselenophosphinate) nickel(II), Ni[ i Pr 2 P(S)NP(Se) i -Pr 2 ] 2 , an interesting complex used as SSP for the growth of nickel phosphide (Ni 2 P) or nickel selenide (Ni 0.85 Se) and in sequence for Ni 0.85 Se/Ni 2 P layers. There are reports for the formation of different phases of the same material from a SSP 12 but to best of our knowledge there are no reports for the deposition of phosphide and selenide materials from the same precursor.The SSP was synthesized by the deprotonation of the ligand [ i -Pr 2 P(S)NHP(Se) i Pr 2 ] 13 using sodium methoxide to form the anion which is subsequently reacted with nickel(II) nitrate hexahydrate in methanol to produce a dark-red precipitate. Recrystallization of the complex from toluene gave red crystals. X-ray crystallographic studies reveal that a nickel atom is tetrahedrally coordinated through the sulfur and selenium atoms (Figure 1). The crystal structure shows the presence of independent monomeric units which are separated by normal van der Waals distances. The sulfur and selenium atoms are disordered as observed for the Pt[ i Pr 2 P(S)-NHP(Se) i Pr 2 ] 13 complex and are refined with equal occupancies for both atoms. The six-membered NiSSeP 2 N ring adopts puckered pseudo-boat conformation.Decomposition was studied by thermogravimetric analysis (TGA) (N 2 atmosphere at 10 °C min -1 ) which reveals a single-step decomposition between 300 and 368 °C. Low-pressure metalorganic (LP-MOCVD) experiments were carried out using a custom-built cold-walled low-pressure reactor tube which has been described elsewhere. 14 Deposition was carried out on a glass substrate for 60 min at temperatures between 475 and 375 °C, and the precursor temperature was kept constant at 300 °C. Nickel phosphide films were deposited at temperatures of 475, 450, and 425 °C, whereas nickel selenide films were deposited at temperatures of 400 or 375 °C. X-ray diffraction pattern (XRD) of the

Optical and structural characterization of nickel selenide nanoparticles synthesized by simple methods

“…The challenges associated with these methods are the lack of manipulation and the ability to monitor the reaction conditions during synthesis. The single-source precursor method has been reported for the synthesis of nickel selenide thin films via the CVD method but to our knowledge has not been used for the preparation of the equivalent nanopowders [26].…”

Experimental and Theoretical Investigations of the Contact Ion Pairs Formed by Reactions of the Anions [(EPR2)2N]− (R = iPr, tBu; E = S, Se) with the Cations [(TePR2)2N]+ (R = iPr, tBu)

“…The primary focus has been the coordination chemistry of these bidentate ligands, and several reviews that provide details of the complexes of 1 with a diverse array of main group, lanthanide and transition metals have been published. [3][4][5] A significant recent application of these complexes, particularly in the case of the selenium derivative (1, E = Se, R = i Pr), has been as single-source precursors for the generation of metal selenides in the form of semiconducting thin films [6][7][8][9][10][11][12][13][14][15][16][17] or quantum dots 18 via CVD or solvothermal processes.…”

Synthesis and characterization of nickel selenide nanoparticles: size and shape determining parameters

“…Therefore in this study factors that affect the reaction environment are monitored and their influences on the properties of the nanoparticles are investigated. Nickel selenide is a p-type semiconductor with a bulk energy band-gap of 2.0 eV (620-nm) [19,21]. Because it is a Pauli magnet a lot of interest has been directed to the synthesis of nickel selenide [22].…”