Hydrogen gas generation using n-GaN photoelectrodes with immersed Indium Tin Oxide ohmic contacts

Liu, Shu Yen; Lin, Yu Chuan; Ye, Jhao Cheng; Tu, Shang Ju; Huang, Fenglan; Lee, M. L.; Lai, Wei–Chih; Sheu, Jinn-Kong

doi:10.1364/oe.19.0a1196

Cited by 13 publications

(4 citation statements)

References 17 publications

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“…Here, an aqueous solution of NaCl was used as an electrolyte to decrease the O 2 overpotential for PEC water splitting. [60][61][62] This is because Cl À ions, competing with OH À ions, could be oxidized by photogenerated holes at the photoanode. 63,64 Upon illumination, the undoped a-Fe 2 O 3 lm (0TiFe lm) shows an observable photocurrent in the range of several mA cm À2 at 0.05 V which continues to increase to 0.045 mA cm À2 at 1.0 V. In comparison to the undoped a-Fe 2 O 3 lm, the Ti-doped a-Fe 2 O 3 lms show much higher photocurrents at 1.0 V (Fig.…”

Section: Pec and Electrochemical Propertiesmentioning

confidence: 99%

Physical and photoelectrochemical characterization of Ti-doped hematite photoanodes prepared by solution growth

et al. 2013

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We present the fabrication and characterization of Ti-doped hematite (a-Fe 2 O 3 ) films for application as photoanodes in photoelectrochemical (PEC) cells for water splitting. It is demonstrated that Ti doping significantly improves the PEC activity as the photocurrent at 1.0 V vs. Ag/AgCl electrode for a 400 nm thick Ti-doped film (0.66 mA cm À2 ) was found to be $14 times higher than that of an undoped film (0.045 mA cm À2 ). The films were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and ultrafast transient absorption spectroscopy to obtain information about their structural, electronic, and charge carrier dynamic properties. Based on characterization of the chemical states of the involved elements as well as the charge carrier dynamics of the films with Ti doping, it appears that the photocurrent enhancement is related to an increase in charge carrier density or reduced electron-hole recombination. The highest incident photon conversion efficiency (IPCE) measured for this system was 27.0% at 360 nm at a potential of 1.23 V vs. reversible hydrogen electrode (RHE), which was obtained on a 400 nm thick Ti-doped a-Fe 2 O 3 film.

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Section: Pec and Electrochemical Propertiesmentioning

confidence: 99%

Physical and photoelectrochemical characterization of Ti-doped hematite photoanodes prepared by solution growth

et al. 2013

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“…Indium-tin-oxide (ITO), one kind of heavily-doped transparent conductive oxides (TCOs), has been widely employed as transparent conducting electrode and direct-Ohmic contact layers in optoelectronic devices, due to its high transmittance and low resistivity in the visible [1][2][3][4][5]. More recently, ITO nanomaterials, e.g.…”

Section: Introductionmentioning

confidence: 99%

Broadband terahertz conductivity and optical transmission of indium-tin-oxide (ITO) nanomaterials

Yang¹,

Chang²,

Chen³

et al. 2013

Opt. Express

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Indium-tin-oxide (ITO) nanorods (NRs) and nanowhiskers (NWhs) were fabricated by an electron-beam glancing-angle deposition (GLAD) system. These nanomaterials are of interests as transparent conducting electrodes in various devices. Two terahertz (THz) time-domain spectrometers (TDS) with combined spectral coverage from 0.15 to 9.00 THz were used. These allow accurate determination of the optical and electrical properties of such ITO nanomaterials in the frequency range from 0.20 to 4.00 THz. Together with Fourier transform infrared spectroscopic (FTIR) measurements, we found that the THz and far-infrared transmittance of these nanomaterials can be as high as 70% up to 15 THz, as opposed to about 9% for sputtered ITO thin films. The complex conductivities of ITO NRs, NWhs as well films are well fitted by the Drude-Smith model. Taking into account that the volume filling factors of both type of nanomaterials are nearly same, mobilities, and DC conductivities of ITO NWhs are higher than those of NRs due to less severe carrier localization effects in the former. On the other hand, mobilities of sputtered ITO thin films are poorer than ITO nanomaterials because of larger concentration of dopant ions in films, which causes stronger carrier scattering. We note further that consideration of the extreme values of Re{σ} and Im{σ} as well the inflection points, which are functions of the carrier scattering time (τ) and the expectation value of cosine of the scattering angle (γ), provide additional criteria for accessing the accuracy of the extraction of electrical parameters of non-Drude-like materials using THz-TDS. Our studies so far indicate ITO NWhs with heights of ~1000 nm show outstanding transmittance and good electrical characteristics for applications such as transparent conducting electrodes of THz Devices.

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“…Accordingly, the development of a transparent conductive oxide (TCO) film for ohmic contact to the n-GaN was essential to improve the performance of the device by enhancing the optical transmittance as well as spreading the current transmission. To date, only a few papers have reported the preparation of the TCO electrode contact to n-GaN and the structures showed ohmic contact behavior only through an additional process on the contact's structure or using a highly-doped n-GaN epilayer [6][7][8][9]. In addition, some researchers have used a thin Ti or In interlayer inset between the TCO/n-GaN interface to provide a nonalloyed ohmic contact system [10,11].…”

Section: Introductionmentioning

confidence: 99%

Investigations on the Cosputtered ITO-ZnO Transparent Electrode Ohmic Contacts to n-GaN

et al. 2016

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Transparent indium tin oxide (ITO) and cosputtered ITO-zinc oxide (ZnO) films' contacts to an n-GaN epilayer were investigated. Both of these electrodes' contact to the n-GaN epilayer showed Schottky behavior, although the contact resistance of the ITO-ZnO/n-GaN system was lower than that of the ITO/n-GaN system. By placing a thin Ti interlayer between the ITO-ZnO/n-GaN interface, nonalloyed ohmic contact was achieved. The inset Ti interlayer was both beneficial both for enhancing the outdiffusion of the nitrogen atoms at the surface of the n-GaN and suppressing the indiffusion of oxygen atoms from the surface of the ITO-ZnO to n-GaN. The figure-of-merit (FOM), evaluated from the specific contact resistance and optical property of the Ti/ITO-ZnO system's contact to the n-GaN epilayer, was optimized further at an adequate thickness of the Ti interlayer.

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Hydrogen gas generation using n-GaN photoelectrodes with immersed Indium Tin Oxide ohmic contacts

Cited by 13 publications

References 17 publications

Physical and photoelectrochemical characterization of Ti-doped hematite photoanodes prepared by solution growth

Physical and photoelectrochemical characterization of Ti-doped hematite photoanodes prepared by solution growth

Broadband terahertz conductivity and optical transmission of indium-tin-oxide (ITO) nanomaterials

Investigations on the Cosputtered ITO-ZnO Transparent Electrode Ohmic Contacts to n-GaN

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