Reactive sputter deposition of pyrite structure transition metal disulfide thin films: Microstructure, transport, and magnetism

Baruth, A.; Manno, Michael; Narasimhan, D.; Shankar, A.; Zhang, X.; Johnson, Melissa; Aydil, Eray S.; Leighton, C.

doi:10.1063/1.4751358

Cited by 16 publications

(14 citation statements)

References 41 publications

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“…It is worth noting in fact that in our recent prior work on reactively sputtered FeS 2 a F = F 0 exp (T 0 /T) 1/2 dependence was also observed. 26 Further work will be required to fully understand the generality of such behavior in FeS 2 synthesized by other methods.…”

Section: Quantification Of the Results Frommentioning

confidence: 99%

Crossover From Nanoscopic Intergranular Hopping to Conventional Charge Transport in Pyrite Thin Films

et al. 2013

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Pyrite FeS2 is receiving a resurgence of interest as a uniquely attractive thin film solar absorber based on abundant, low-cost, nontoxic elements. Here we address, via ex situ sulfidation synthesis, the long-standing problem of understanding conduction and doping in FeS2 films, an elusive prerequisite to successful solar cells. We find that an abrupt improvement in crystallinity at intermediate sulfidation temperatures is accompanied by unanticipated crossovers from intergranular hopping to conventional transport, and, remarkably, from hole-like to electron-like Hall coefficients. The hopping is found to occur between a small volume fraction of conductive nanoscopic sulfur-deficient grain cores (beneath our X-ray diffraction detection limits), embedded in nominally stoichiometric FeS2. In addition to placing constraints on the conditions under which useful properties can be obtained from FeS2 synthesized in diffusion-limited situations, these results also emphasize that FeS2 films are not universally p-type. Indeed, with no knowledge of the active transport mechanism we demonstrate that the Hall coefficient alone is insufficient to determine the sign of the carriers. These results elucidate the possible transport mechanisms in thin film FeS2 in addition to their influence on the deduced carrier type, an enabling advancement with respect to understanding and controlling doping in pyrite films.

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Section: Quantification Of the Results Frommentioning

confidence: 99%

Crossover From Nanoscopic Intergranular Hopping to Conventional Charge Transport in Pyrite Thin Films

et al. 2013

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“…The sputtering deposition, [125][126][127][128][129] microwave, [130][131][132] plasma, 91,124 magnetic eld, 133 electrochemical deposition, 134 pulsed electron ablation 135 and mechanical milling 136 were employed to synthesize iron pyrite. However, not all of these highly efficient methods could be the appropriate ones to synthesize iron pyrite crystals with the designed morphologies.…”

Section: Synthesis Of Iron Pyrite With Other Methods Of Relatively Himentioning

confidence: 99%

Morphology controllable syntheses of micro- and nano-iron pyrite mono- and poly-crystals: a review

Huang

Zhu

2016

RSC Adv.

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Synthesis of iron pyrite with defined morphology has long been actively pursued, due to the strong size and shape dependence of their chemical and physical properties. This review provides comprehensive information outlining current knowledge regarding the morphology controllable syntheses of micro-and nano-iron pyrite mono-and poly-crystals. The wet-chemical methods are summarized as the controllable syntheses, including the hydrothermal, solvothermal, hot-injection and heating-up methods, sulphidation and methods with other relatively high efficiencies. The present study reveals the discussion of relationship between the morphologies and major controlling factors, the temperature, precursor chemicals, solvents and surfactants. The existing challenges for future fine tuning of iron pyrite facets are also proposed for improving the performance of iron pyrite based materials.

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“…The decrease of the T eff during the first 40 µs is consistent with other observations in non-reactive and reactive HiPIMS systems. Plasma pulse onset is accompanied by beam-like electrons with energy of roughly 100 eV at the probe position, which are reflected from the negative space charge sheath around the cathode [4]. The minimum of T eff within the plasma pulse having magnitude between 1.0 eV and 1.2 eV (depending on the H 2 S mass flow rate) is probably connected with massive ionization of sputtered particles that have much lower ionization potential than argon atoms (Fe ionization potential is around 7.9 eV).…”

Section: Resultsmentioning

confidence: 99%

“…A lot of effort was devoted to the research of direct-current (DC) or radio frequency (RF) sputtering methods of various sulfides [1][2][3]. These can be semiconductor materials for example iron disulfide FeS 2 in the pyrite phase reported as a p-type semiconductor [1,2,4] or an n-type semiconductor suitable as a photoanode in solar water splitting cells when the pyrite phase was mixed with a small fraction of marcasite [5]. FeS 2 was investigated for various applications such as absorbing material in solar cells, material for photocatalysis or electrocatalysis [6].…”

Section: Introductionmentioning

confidence: 99%

“…The high absorption coefficient, α = 6 × 10 5 cm −1 for λ = 633 nm [7], which is several orders of magnitude larger than that of crystalline silicon, and the composition of abundant, cheap, and non-toxic elements makes pyrite an interesting material for solar cells and further photonic applications [1,[8][9][10][11][12][13]. FeS 2 thin films with promising semiconductor properties were also prepared by reactive magnetron sputtering of an Fe target in Ar + H 2 S gas mixture [1,2,4].…”

Section: Introductionmentioning

confidence: 99%

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Plasma Diagnostics in Reactive High-Power Impulse Magnetron Sputtering System Working in Ar + H2S Gas Mixture

et al. 2020

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A reactive high-power impulse magnetron sputtering system (HiPIMS) working in Ar + H 2 S gas mixture was investigated as a source for the deposition of iron sulfide thin films. As a sputtering material, a pure Fe target was used. Plasma parameters in this system were investigated by a time-resolved Langmuir probe, radio-frequency (RF) ion flux probe, quartz crystal monitor modified for measurement of the ionized fraction of depositing particles, and by optical emission spectroscopy. A wide range of mass flow rates of reactive gas H 2 S was used for the investigation of the deposition process. It was found that the deposition rate of iron sulfide thin films is not influenced by the flow rate of H 2 S reactive gas fed into the magnetron discharge although the target is covered by iron sulfide compound. The ionized fraction of depositing particles decreases from r ≈ 40% to r ≈ 20% as the flow rate of H 2 S, Q H 2 S , changes from 0 to 19 sccm at the gas pressure around p ≈ 1 Pa in the reactor chamber. The electron concentration n e measured by the Langmuir probe at the position of the substrate decreases over this change of Q H 2 S from 10 18 down to 10 17 m −3Coatings 2020, 10, 246 2 of 16 realized. Furthermore, FeS films were found to be excellent low-friction materials working like solid state lubricants in tribological applications [16].High-power impulse magnetron sputtering system (HiPIMS) is a relatively novel approach for the deposition of thin films [17][18][19][20]. This method utilizes very high discharge current densities during the pulse j D > 1 A cm −2 , but, simultaneously, average power applied in the HiPIMS discharge is similar to DC magnetron sputtering. These conditions result in a high degree of ionization of sputtered particles. Thus, the deposited films have higher density, better adhesion, and 3D objects such as trenches, etc. and can be more uniformly coated as well [21][22][23]. Recently, reactive HiPIMS in various gas mixtures has been used for the deposition of oxides, nitrides, and other materials [24][25][26][27][28][29][30][31].In this paper, we will present the first study of plasma parameters in the reactive HiPIMS in Ar + H 2 S gas mixture whose results could be further used for the optimization of deposition of iron sulfide thin films or other types of sulfides. ExperimentalThe experimental setup of the reactive HiPIMS in Ar + H 2 S gas mixture can be seen in Figure 1. The system is equipped with a pure iron Fe target with an outer diameter of 50 mm and a thickness of 0.8 mm. The stainless-steel reactor vacuum chamber is continuously pumped by a combination of turbomolecular (pumping speed S t = 250 L·s −1 ) and rotary vane pumps (pumping speed S r = 25 m 3 h −1 ). The gas flow rates of Ar (99.9999%) and pure H 2 S (99.5%) are independently controlled by two mass flow controllers. It is useful to note that H 2 S is an inflammable and highly toxic gas. Consequently, the use of H 2 S in a laboratory is subject to approval by a respective official body. The pressure in the reactor cham...

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Reactive sputter deposition of pyrite structure transition metal disulfide thin films: Microstructure, transport, and magnetism

Cited by 16 publications

References 41 publications

Crossover From Nanoscopic Intergranular Hopping to Conventional Charge Transport in Pyrite Thin Films

Crossover From Nanoscopic Intergranular Hopping to Conventional Charge Transport in Pyrite Thin Films

Morphology controllable syntheses of micro- and nano-iron pyrite mono- and poly-crystals: a review

Plasma Diagnostics in Reactive High-Power Impulse Magnetron Sputtering System Working in Ar + H2S Gas Mixture

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