Epitaxial p-type SiC as a self-driven photocathode for water splitting

Kato, Masashi; Yasuda, Tomonari; Miyake, Koji; Ichimura, M.; Hatayama, Tomoaki

doi:10.1016/j.ijhydene.2014.01.049

Cited by 27 publications

(36 citation statements)

References 24 publications

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“…Recently, fluorescent silicon carbide using boron doped 6H-SiC was introduced for a white light emitting diode concept for general lighting [17,18]. Besides attractive to explore in photovoltaics, hydrogen generation by water splitting can be developed by using cubic silicon carbide as a photo-electrode to absorb and convert solar energy into gaseous hydrogen and oxygen via a photoelectrochemical (PEC) water-splitting cell [19]. Among all commonly used semiconductors, 3C-SiC has outstanding properties to convert visible sunlight energy and water into hydrogen fuel.…”

Section: Resultsmentioning

confidence: 99%

Cubic silicon carbide as a potential photovoltaic material

Syväjärvi

Jokubavičius

et al. 2016

Solar Energy Materials and Solar Cells

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In this work we present a significant advancement in cubic silicon carbide (3C-SiC) growth in terms of crystal quality and domain size, and indicate its potential use in photovoltaics. To date, the use of 3C-SiC for photovoltaics has not been considered due to the band gap of 2.3 eV being too large for conventional solar cells. Doping of 3C-SiC with boron introduces an energy level of 0.7 eV above the valence band. Such energy level may form an intermediate band (IB) in the band gap. This IB concept has been presented in the literature to act as an energy ladder that allows absorption of sub-bandgap photons to generate extra electron-hole pairs and increase the efficiency of a solar cell. The main challenge with this concept is to find a materials system that could realize such efficient photovoltaic behavior. The 3C-SiC bandgap and boron energy level fits nicely into the concept, but has not been explored for an IB behavior.For a long time crystalline 3C-SiC has been challenging to grow due to its metastable nature. The material mainly consists of a large number of small domains if the 3C polytype is maintained. In our work a crystal growth process was realized by a new approach that is a combination of initial nucleation and step-flow growth. In the process, the domains that form initially extend laterally to make larger 3C-SiC domains, thus leading to a pronounced improvement in crystalline quality of 3C-SiC. In order to explore the feasibility of IB in 3C-SiC using boron, we have explored two routes of introducing boron impurities; ion implantation on un-doped samples and epitaxial growth on un-doped samples using pre-doped source material. The results show that 3C-SiC doped with boron is an optically active material, and thus is interesting to be further studied for IB behavior.For the ion implanted samples the crystal quality was maintained even after high implantation doses and subsequent annealing. The same was true for the samples grown with pre-doped source material, even with a high concentration of boron impurities.We present optical emission and absorption properties of as-grown and boron implanted 3C-SiC. The low-temperature photoluminescence spectra indicate the formation of optically active deep boron centers, which may be utilized for achieving an IB behavior at sufficiently high dopant concentrations. We also discuss the potential of boron doped 3C-SiC base material in a broader range of applications, such as in photovoltaics, biomarkers and hydrogen generation by splitting water.

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Section: Resultsmentioning

confidence: 99%

Cubic silicon carbide as a potential photovoltaic material

Syväjärvi

Jokubavičius

et al. 2016

Solar Energy Materials and Solar Cells

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“…Up to now,T iO 2 hasb een considered the reference n-type SC materialo wing to its high photoactivity,n ontoxicity, inertness, low cost, and abundance on earth. Non-oxide materials, such as Si, [6][7][8][9] SiC, [10][11][12] and InP, [13,14] are among the most extensively studied. [2,4,5] On the other hand, in relation with p-type semiconductors, finding ah ighly efficient, low cost, and stable photocathoder emains ap ending task.…”

Section: Introductionmentioning

confidence: 99%

Study of Copper Ferrite as a Novel Photocathode for Water Reduction: Improving Its Photoactivity by Electrochemical Pretreatment

2016

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Studies on water-splitting p-type oxide electrodes based on nontoxic earth-abundant elements are scarce. Herein, the behavior of electrodes composed of CuFe2 O4 nanoparticles 30 nm in size is presented. The as-prepared CuFe2 O4 nanoporous electrodes exhibit small anodic photocurrents in 0.1 m NaOH. However, an electrochemical pretreatment consisting in the application of sufficiently positive potentials leads to p-type behavior with a photocurrent onset as high as 1.1 V versus the reversible hydrogen electrode, which is among the most positive values reported for an oxide absorbing visible light (band gap of 2.1 eV). This photocurrent is partly due to H2 evolution, but there are also signs of photoreduction of the material. Although the photocurrents are modest, these results point to the possibility of using CuFe2 O4 as a photocathode material in water-splitting devices. Furthermore, the strategy employed for the enhancement in the CuFe2 O4 photoactivity could be extended to other photocathode materials.

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“…13 Some other materials have also been studied but are often limited by either rapid degradation 14 or very poor absorption of visible light. 15 To effectively utilize photons within a wide range of the solar spectrum, a dual light absorber with a narrow bandgap material like Si at the bottom and direct wide-bandgap materials on top can provide energetic electrons for H 2 production. However, the design and performance of such multijunction devices is limited by the current matching related issues between the two absorbers, because the carrier collection and extraction is only available on the front surfaces.…”

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confidence: 99%

High Efficiency Solar-to-Hydrogen Conversion on a Monolithically Integrated InGaN/GaN/Si Adaptive Tunnel Junction Photocathode

et al. 2015

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H2 generation under sunlight offers great potential for a sustainable fuel production system. To achieve high efficiency solar-to-hydrogen conversion, multijunction photoelectrodes have been commonly employed to absorb a large portion of the solar spectrum and to provide energetic charge carriers for water splitting. However, the design and performance of such tandem devices has been fundamentally limited by the current matching between various absorbing layers. Here, by exploiting the lateral carrier extraction scheme of one-dimensional nanowire structures, we have demonstrated that a dual absorber photocathode, consisting of p-InGaN/tunnel junction/n-GaN nanowire arrays and a Si solar cell wafer, can operate efficiently without the strict current matching requirement. The monolithically integrated photocathode exhibits an applied bias photon-to-current efficiency of 8.7% at a potential of 0.33 V versus normal hydrogen electrode and nearly unity Faradaic efficiency for H2 generation. Such an adaptive multijunction architecture can surpass the design and performance restrictions of conventional tandem photoelectrodes.

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Epitaxial p-type SiC as a self-driven photocathode for water splitting

Cited by 27 publications

References 24 publications

Cubic silicon carbide as a potential photovoltaic material

Cubic silicon carbide as a potential photovoltaic material

Study of Copper Ferrite as a Novel Photocathode for Water Reduction: Improving Its Photoactivity by Electrochemical Pretreatment

High Efficiency Solar-to-Hydrogen Conversion on a Monolithically Integrated InGaN/GaN/Si Adaptive Tunnel Junction Photocathode

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