Analysis of time-resolved photocurrent transients at semiconductor/liquid interfaces

Kenyon, C.; Ryba, Gail N.; Lewis, Nathan S.

doi:10.1021/j100151a048

Cited by 19 publications

(27 citation statements)

References 7 publications

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“…This criterion eliminated the possibility of photocarrier generation via optical absorption of the SHG source when 2បϾE gap . The dopant concentration dependence was consistent with previous photocurrent studies of n-TiO 2 in an aqueous electrolyte 16 where the transient response was attributed to the nonfaradaic charging of the double layer capacitance (C dl ) of the interface as opposed to minority carrier transfer across the junction. The transient photocurrent was measured as a voltage drop across a 50 ⍀ resistor between the two electrodes in the cell, amplified with a fast preamplifier, and processed with a gated integrator.…”

Section: ͓S0003-6951͑96͒04240-4͔supporting

confidence: 88%

“…15 The intensity of the incident laser was varied with a set of linear polarizers and monitored with a photodi-a͒ Electronic mail: jmiragli@aplcomm.jhuapl.edu ode. A discussed by Wilson et al 17 and Kenyon et al, 16 the relatively large value of C dl (ϳ10 F͒ limits the transient contribution from the hole transport across the interface since this is not an energetically favorable pathway for discharging the photocarrier population. In all measurements, care was taken to minimize the photocarrier density in the depletion layer so as not to significantly screen the dc field in the semiconductor.…”

Section: ͓S0003-6951͑96͒04240-4͔mentioning

confidence: 96%

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Transient photocurrent induced in gallium nitride by two-photon absorption

Miragliotta

Wickenden

1996

Applied Physics Letters

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Section: ͓S0003-6951͑96͒04240-4͔supporting

confidence: 88%

Section: ͓S0003-6951͑96͒04240-4͔mentioning

confidence: 96%

Transient photocurrent induced in gallium nitride by two-photon absorption

Miragliotta

Wickenden

1996

Applied Physics Letters

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“…After such an intense injection pulse in a short time period, the equilibrium electric field in the semiconductor is virtually eliminated by the presence of a high concentration of both minority and majority free carriers near the surface. 27,35,51,82,83 Figures 2a-d illustrate the simulated photoluminescence decay dynamics for a range of different values of k ht as a function of the surface state density, N t,s . Four different N t,s values were used, ranging from 10 9 to 10 15 cm -2 , to produce corresponding low-level minority carrier surface recombination velocities, S p , ranging from 10 1 to 10 7 cm s -1 .…”

Section: Simulation Resultsmentioning

confidence: 99%

“…These simulations are of importance because in many experiments the illumination intensity is increased by focusing a laser beam to attain intermediate injection levels using routinely available laser beam powers. 30,35 Without a complete threedimensional simulation routine, the most reliable comparison between simulations and experimental data will be obtained through use of uniform, homogeneous illumination of the sample and reference to the simulations depicted in Figures 2-5.…”

Section: B Low-level Injection Simulations At the Flat-bandmentioning

confidence: 99%

Conditions Under Which Heterogeneous Charge-Transfer Rate Constants Can Be Extracted from Transient Photoluminescence Decay Data of Semiconductor/Liquid Contacts As Determined by Two-Dimensional Transport Modeling

et al. 1998

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An extensive series of digital simulations of the decay dynamics of photoexcited charge carriers at a semiconductor/liquid interface has been performed using the two-dimensional simulation code ToSCA. ToSCA treats majority and minority carrier capture processes separately and incorporates field-dependent carrier mobility terms. These features produce dramatic differences in the output parameters obtained when fitting experimental data with ToSCA relative to those obtained by fitting such data with prior, less complete, simulations. The simulations revealed that for a typical (n-type in our example) InP electrode in contact with outer-sphere redox reagents dissolved in the liquid phase the photoluminescence decays were generally insensitive to the value of the minority carrier charge-transfer rate constant, k ht . Instead, diffusion and driftinduced separation of photogenerated carriers in the space-charge layer of the semiconductor dominated the time decay of the observed luminescence signal under most experimentally accessible conditions. Values of k ht and of the minority carrier low-level surface recombination velocity, S p , could be obtained from an analysis of the photoluminescence decays only when the following restricted sets of conditions were satisfied simultaneously: 10 1 cm s -1 e S p e 10 5 cm s -1 , 10 -18 cm 4 s -1 e k ht e 10 -15 cm 4 s -1 , and the electrode potential, E, was in the region 0 < E < +0.15 V relative to the flat-band potential of the n-type semiconductor/ liquid interface. The simulations demonstrated that it was not possible to extract a "field dependence" of the charge-transfer rate constant when the semiconductor/liquid contact was maintained in reverse bias (E g +0.15 V vs the flat-band potential) and was subjected to light pulses that produced low or moderate carrier injection levels. Under such conditions, the photoluminescence decay dynamics were dominated by driftinduced charge separation in the space-charge layer of the semiconductor. Under high-level injection conditions, no "field dependence" could be observed because the majority of the photoluminescence decay dynamics occurred near the flat-band condition, so the value of the band bending in the semiconductor under dark, equilibrium conditions had negligible influence on the luminescence transients produced by a high-intensity laser pulse. Additionally, comparison between one-dimensional and two-dimensional simulations showed that use of one-dimensional simulation routines to extract S p and k ht values from experimental data obtained using focused laser beam excitation can lead to severe overestimates of interfacial charge-transfer rates.

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“…14 In the recent past a number of other groups have started to apply microwave or high frequency reflectometry in combination with conventional electrochemical methods in order to get more information about the complex charge carrier kinetics at semiconductor/electrolyte interfaces. [15][16][17][18] The photoinduced microwave reflection signal is proportional to the integrated excess charge carrier profile. 19,20 For given boundary conditions at the front and rear face, the sta-tionary profile is correlated to the surface concentration of excess carriers as outlined in.…”

Section: Introductionmentioning

confidence: 99%