Monolithic Light Emitting Diode Arrays using Gallium Phosphide

Carter, M. A.; Mottram, Alexander D.; Peaker, А. R.; Sudlow, P. D.; White, Thomas P.

doi:10.1038/232469b0

Cited by 5 publications

(5 citation statements)

References 3 publications

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“…Second, GaP natively demonstrates surface energetics amenable to both proton and CO 2 reduction, − indicating that dye-sensitized schemes could be used to drive these specific half reactions. Third, GaP is a technologically mature material (e.g., used extensively in commercial light emitting diodes), so methods for its metallurgy (i.e., doping, contacting) are well-known . Nevertheless, the use of GaP as a dye-sensitized photocathode platform in water is challenging for several reasons.…”

Section: Introductionmentioning

confidence: 99%

“…Third, GaP is a technologically mature material (e.g., used extensively in commercial light emitting diodes), so methods for its metallurgy (i.e., doping, contacting) are wellknown. 18 Nevertheless, the use of GaP as a dye-sensitized photocathode platform in water is challenging for several reasons. First, the surface of GaP is not indefinitely stable in water.…”

Section: ■ Introductionmentioning

confidence: 99%

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Sensitization of p-GaP by Physisorbed Triarylmethane Dyes

2018

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p-Type gallium phosphide (GaP) electrodes have been sensitized by triarylmethane dyes physisorbed from aqueous solutions. This work is the first to show light-stimulated hole injection from an adsorbed molecular chromophore on native GaP surfaces. Freshly etched p-GaP(100) and p-GaP(111)A electrodes were loaded with physisorbed dye by brief soaking in solutions of Fast Green. X-ray photoelectron spectroscopy, corroborated by Auger electron spectroscopy, indicated that such treatments yield undetectable surface coverages. However, steady-state photoelectrochemical responses consistently showed that sub-bandgap photoresponses were commensurate with light absorption by the adsorbed dye. The photoresponse characteristics were clearly insensitive to the identity and amount of intended redox mediators dissolved in solution at low light intensities. Instead, the data suggest electrochemically active surface states related to the cathodic degradation of GaP can accept electrons from photoexcited physisorbed dye. Measurements at high illumination intensities showed sensitivity toward redox mediators in solution, indicating that the conventional mode of dye regeneration by redox species in solution is possible with p-GaP. Separate measurements with covalently modified p-GaP(111)A photoelectrodes further suggested that deliberate modification to minimize/eliminate surface states is also possible. Collectively, this work indicates that although some types of dye readily adsorb onto native GaP interfaces, the low dye loadings and the susceptibility of the interface to chemical attack during the sensitization process argue against using bare p-GaP photocathodes with physisorbed triarylmethane dyes. Instead, these studies suggest that dye-sensitized photocathodes based on p-GaP require deliberate surface chemical modification methods to overcome the low loading and inhibit unwanted charge transfer between the surface and the photoexcited dye.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Sensitization of p-GaP by Physisorbed Triarylmethane Dyes

2018

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“…P-type gallium phosphide (GaP) is a potential photocathode material for photoelectrochemical applications. − Relative to other semiconductors actively being studied or developed as photocathodes in photoelectrochemical cells, p-GaP has three tangible advantages. First, it is already a technologically relevant semiconductor material with a preexisting infrastructure for production at large scales . Second, GaP has a favorable midsized bandgap ( E g = 2.26 eV) that offers the possibility of a large photovoltage and an appreciable photocurrent (i.e., >10 mA cm –2 ) under illumination with sunlight at an intensity of 100 mW cm –2 . , Third, crystalline GaP can possess charge carrier mobilities much larger than those of known metal oxide semiconductors. , Nevertheless, the use of GaP also has two tangible and formidable drawbacks.…”

Section: Introductionmentioning

confidence: 99%

“…First, it is already a technologically relevant semiconductor material with a preexisting infrastructure for production at large scales. 8 Second, GaP has a favorable midsized bandgap (E g = 2.26 eV) that offers the possibility of a large photovoltage and an appreciable photocurrent (i.e., >10 mA cm −2 ) under illumination with sunlight at an intensity of 100 mW cm −2 . 9,10 Third, crystalline GaP can possess charge carrier mobilities much larger than those of known metal oxide semiconductors.…”

Section: ■ Introductionmentioning

confidence: 99%

Macroporous p-GaP Photocathodes Prepared by Anodic Etching and Atomic Layer Deposition Doping

Lee

Bielinski

Fahrenkrug

et al. 2016

ACS Appl. Mater. Interfaces

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P-type macroporous gallium phosphide (GaP) photoelectrodes have been prepared by anodic etching of an undoped, intrinsically n-type GaP(100) wafer and followed by drive-in doping with Zn from conformal ZnO films prepared by atomic layer deposition (ALD). Specifically, 30 nm ALD ZnO films were coated on GaP macroporous films and then annealed at T = 650 °C for various times to diffuse Zn in GaP. Under 100 mW cm(-2) white light illumination, the resulting Zn-doped macroporous GaP consistently exhibit strong cathodic photocurrent when measured in aqueous electrolyte containing methyl viologen. Wavelength-dependent photoresponse measurements of the Zn-doped macroporous GaP revealed enhanced collection efficiency at wavelengths longer than 460 nm, indicating that the ALD doping step rendered the entire material p-type and imparted the ability to sustain a strong internal electric field that preferentially drove photogenerated electrons to the GaP/electrolyte interface. Collectively, this work presents a doping strategy with a potentially high degree of controllability for high-aspect ratio III-V materials, where the ZnO ALD film is a practical dopant source for Zn.

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“…The luminescence effects of the isoelectronic impurity nitrogen in GaP have been the subject of considerable study (Thomas et al 1965, Thomas and Hopfield 1966, Faulkner 1968, Allen 1971, Faulkner et al 1969, and Logan et al (1968) have shown that highefficiency green electroluminescence can be obtained from nitrogen-doped GaP diodes grown by the double liquid epitaxy process. Since then there have been several reports of high efficiencies from nitrogen-doped diodes (Logan et al 1971, Carter et al 1971, Nicklin et a1 1971, Ladany and Kressel 1972, but in none of these reports is the device operation clear. For example, the region of the p-n junction responsible for the luminescence, the light output characteristics and the effect of changing the p-and n-type carrier concentration on the diode efficiency were not understood.…”

Section: Introductionmentioning

confidence: 99%

Green electroluminescence in GaP diodes and its correlation with cathodoluminescence measurements

Wight

Birbeck

Trussler

et al. 1973

J. Phys. D: Appl. Phys.

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The results of a programme of research on green-emitting epitaxial diodes are reported. Diode quantum efficiencies of 0·07% DC and 0·40% pulsed have been obtained from an optimized structure. Room-temperature cathodoluminescence measurements on the bulk regions of device structures are correlated with diode performance. Major correlations are found in luminescence efficiency, light output characteristics and spectral distribution; the last is analysed in some detail to elucidate the room-temperature luminescence mechanisms. These results, coupled with the results of attempts to change the minority carrier injection ratio in the structure and the analysis of diode characteristics, have enabled the operation of our diodes to be understood in terms of abrupt junction theory.

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Monolithic Light Emitting Diode Arrays using Gallium Phosphide

Cited by 5 publications

References 3 publications

Sensitization of p-GaP by Physisorbed Triarylmethane Dyes

Sensitization of p-GaP by Physisorbed Triarylmethane Dyes

Macroporous p-GaP Photocathodes Prepared by Anodic Etching and Atomic Layer Deposition Doping

Green electroluminescence in GaP diodes and its correlation with cathodoluminescence measurements

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