<i>In situ</i> measurements of GaN photoluminescence at metal and electrolyte contacts

Harvey, Elizabeth; Heffernan, Claire; Buckley, D. H.; O'Raifeartaigh, Cormac

doi:10.1063/1.1518156

Cited by 9 publications

(11 citation statements)

References 22 publications

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“…In ref. 6, it is reported that flat-band potential obtained by PL intensity saturation is in good agreement with that obtained by capacitance measurement using the same n-GaN sample and the same pH, and that the pH dependence obtained is in good agreement with Nernst's equation. The pH dependences reported in refs.…”

supporting

confidence: 79%

Simultaneous Monitoring of Hydrogen Generation and Flat-Band Potential by Measuring Bias Dependent Photoluminescence of n-Type GaN/Electrolyte System

Morita¹,

Narumi²,

Kobayashi³

2006

jjap

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In determining the flat-band potential of n-type GaN in an electrolyte solution by measuring the bias dependence of photoluminescence (PL) intensity, it is shown that, as voltage is applied toward a cathodic direction, the intensities of bandedge and yellow luminescences saturate and PL excitation light is scattered by hydrogen bubbles on a GaN surface simultaneously. The onset voltage of scattered light intensity is in good agreement with voltage showing PL intensity saturation, indicating that the monitoring of scattered light can be used as a technique for detecting hydrogen generation with a high sensitivity. The flat-band potential of n-type GaN thus determined is Àð0:071 Â pH þ 0:582Þ V vs Ag-AgCl for a carrier concentration of 2:8 Â 10 19 cm À3 , which is a larger pH dependence than that expected by Nernst's equation.

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supporting

confidence: 79%

Simultaneous Monitoring of Hydrogen Generation and Flat-Band Potential by Measuring Bias Dependent Photoluminescence of n-Type GaN/Electrolyte System

Morita¹,

Narumi²,

Kobayashi³

2006

jjap

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“…The number of surviving electrons increases almost linearly as the applied potential becomes more positive with intersection of the x-axis at À0.9 V. This x-intercept potential corresponds to the flat band potential of n-type GaN, which is reported in previous papers. 27,28,40 At potentials more positive than the flat band potential, upward band bending is enhanced where electrons and holes are forced to move into the bulk and to the surface, respectively. Therefore, the charge carriers are effectively separated at positive potentials, and hence, the number of photogenerated electron is increased.…”

Section: Dynamics Of Photogenerated Chargementioning

confidence: 99%

Potential-Dependent Recombination Kinetics of Photogenerated Electrons in n- and p-Type GaN Photoelectrodes Studied by Time-Resolved IR Absorption Spectroscopy

et al. 2011

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Recombination kinetics of photogenerated electrons in n-type and p-type GaN photoelectrodes active for H(2) and O(2) evolution, respectively, from water was examined by time-resolved IR absorption (TR-IR) spectroscopy. Illumination of a GaN film with UV pulse (355 nm and 6 ns in duration) gives transient interference spectra in both transmittance and reflection modes. Simulation shows that the interference spectra are caused by photogenerated electrons. We observed that recombination in the microsecond region is greatly affected by the applied potentials, the lifetime becoming longer at negative and positive potentials for n- and p-type GaN electrodes, respectively. There is a good correlation between potential dependence of the steady-state reaction efficiency and that of the number of surviving electrons in the millisecond region. We also performed potential jump measurement to examine the shift in Fermi level by photogenerated charge carriers. In the case of n-type GaN, the electrode potential jumps to the negative side by accumulation of electrons in the bulk. However, in the case of p-type GaN, the electrode potential first jumps to the negative side within 20 μs and gradually shifts to the positive side in a few milliseconds, while the number of charge carriers is constant at >0.2 ms. This two-step process is ascribed to electron transport from the bulk to the surface of GaN, because the electrode potential is sensitive to the number of electrons in the bulk. The results confirm that TR-IR combined with potential jump measurement provides useful information for understanding the behavior of charge carriers in photoelectrochemical systems.

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“…The characterization of the band-edge potential of GaN has been studied by the Mott-Schottky plot in capacitance measurement [1,[3][4][5] and photocurrent measurement [1] and by bias dependence of photoluminescence (PL) [6,7]. In this work, we measured and compared the flat-band potentials of n-GaN and InGaN/GaN QWs using bias dependence of PL intensity.…”

Section: Introductionmentioning

confidence: 99%

Flat-band potentials of GaN and InGaN/GaN QWs by bias-dependent photoluminescence in electrolyte solution

Kobayashi

Morita

Narumi

et al. 2007

Journal of Crystal Growth

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In situ measurements of GaN photoluminescence at metal and electrolyte contacts

Cited by 9 publications

References 22 publications

Simultaneous Monitoring of Hydrogen Generation and Flat-Band Potential by Measuring Bias Dependent Photoluminescence of n-Type GaN/Electrolyte System

Simultaneous Monitoring of Hydrogen Generation and Flat-Band Potential by Measuring Bias Dependent Photoluminescence of n-Type GaN/Electrolyte System

Potential-Dependent Recombination Kinetics of Photogenerated Electrons in n- and p-Type GaN Photoelectrodes Studied by Time-Resolved IR Absorption Spectroscopy

Flat-band potentials of GaN and InGaN/GaN QWs by bias-dependent photoluminescence in electrolyte solution

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