Results of a gallium phosphide photovoltaic junction with an AR coating under concentration of natural sunlight

Allen, Charles R.; Woodall, J. M.; Jeon, Jong-Hyeok

doi:10.1016/j.solmat.2011.05.034

Cited by 20 publications

(17 citation statements)

References 7 publications

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“…Gallium phosphide (E g = 2.26 eV) is an interesting candidate for use as a wide bandgap absorber in tandem PEC cells. Open‐circuit voltages of 1.2 V and 1.5 V have been observed for GaP‐based semiconductor/liquid and p–n homojunctions, respectively 10, 11. Assuming perfect collection of all photoexcited minority carriers, GaP can provide current densities of ∼10 mA cm −2 under Air Mass 1.5 (AM 1.5) illumination.…”

Section: Introductionmentioning

confidence: 99%

Photoelectrochemical Behavior of Planar and Microwire‐Array Si|GaP Electrodes

Strandwitz

Turner-Evans

Tamboli

et al. 2012

Advanced Energy Materials

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Gallium phosphide exhibits a short diffusion length relative to its optical absorption length, and is thus a candidate for use in wire array geometries that allow light absorption to be decoupled from minority carrier collection. Herein is reported the photoanodic performance of heteroepitaxially grown gallium phosphide on planar and microwire‐array Si substrates. The n‐GaP|n‐Si heterojunction results in a favorable conduction band alignment for electron collection in the silicon. A conformal electrochemical contact to the outer GaP layer is produced using the ferrocenium/ferrocene (Fc+/Fc) redox couple in acetonitrile. Photovoltages of ∼750 mV under 1 sun illumination are observed and are attributed to the barrier formed at the (Fc+/Fc)|n‐GaP junction. The short‐circuit current densities of the composite microwire‐arrays are similar to those observed using single‐crystal n‐GaP photoelectrodes. Spectral response measurements along with a finite‐difference‐time‐domain optical model indicate that the minority carrier diffusion length in the GaP is ∼80 nm. Solid‐state current–voltage measurements show that shunting occurs through thin GaP layers that are present near the base of the microwire‐arrays. The results provide guidance for further studies of 3D multi‐junction photoelectrochemical cells.

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Section: Introductionmentioning

confidence: 99%

Photoelectrochemical Behavior of Planar and Microwire‐Array Si|GaP Electrodes

Strandwitz

Turner-Evans

Tamboli

et al. 2012

Advanced Energy Materials

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“…The considerable challenges with both V OC and J SC motivate further study of both growth conditions and device designs for GaP solar cells. While GaP cells have been created by a variety of techniques, including diffusion, 11,12 liquid phase epitaxy, 13,15,[17][18][19] organometallic vapor phase epitaxy, 10 and molecular beam epitaxy (MBE), 24,25 no studies on the effect of growth temperature or emitter thickness on cell performance have been reported.…”

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confidence: 99%

“…3(b)). 10,13,15,[17][18][19]24,25 Compared to our samples without window layers, V OC was also enhanced by 80-150 mV to 1.56 V due to the surface passivation provided by the window. For comparison, we also grew a GaAs solar cell with a 20 nm Al 0.4 Ga 0.6 As window.…”

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confidence: 99%

“…13,15,17,18,24,25 The low L p of 110-200 nm that was previously modeled for n-GaP, as well as the traditionally thinner solar cell emitters in other III-V material systems motivated our choice of a 100 nm emitter thickness. 13,15,17,18 Bittner et al presented the only previous report of a GaP solar cell with an emitter less than 0.5 lm and showed IQE spectra similar to those reported here, though lower in magnitude.…”

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confidence: 99%

“…The relatively low response of our cells for k > 446 nm indicates the need for thicker bases to avoid transmission losses, as well as improved L n in the p-type GaP base. 13,15,[17][18][19]24,25 The results presented here help to build an understanding of suitable growth conditions and device structures for improved GaP solar cells for top-junction applications. As the large increase in T sub from 465 C and 600 C yielded a considerable enhancement in device performance, even higher growth temperatures should be explored to determine if further improvements can be made.…”

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confidence: 99%

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Effects of growth temperature and device structure on GaP solar cells grown by molecular beam epitaxy

Vaisman

Tomasulo

Masuda

et al. 2015

Applied Physics Letters

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Gallium phosphide (GaP) is an attractive candidate for wide-bandgap solar cell applications, possessing the largest bandgap of the III-arsenide/phosphides without aluminum. However, GaP cells to date have exhibited poor internal quantum efficiency (IQE), even for photons absorbed by direct transitions, motivating improvements in material quality and device structure. In this work, we investigated GaP solar cells grown by molecular beam epitaxy over a range of substrate temperatures, employing a much thinner emitter than in prior work. Higher growth temperatures yielded the best solar cell characteristics, indicative of increased diffusion lengths. Furthermore, the inclusion of an AlGaP window layer improved both open-circuit voltage and short wavelength IQE.

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Strong subbandgap photoconductivity in GaP implanted with Ti

Olea

Prado

García-Hemme

et al. 2017

Progress in Photovoltaics

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Photovoltaic solar cells based on the intermediate band (IB) concept could greatly enhance the efficiency of future devices. We have analyzed the electrical and photoconductivity properties of GaP supersaturated with Ti to assess its suitability for IB solar cells. GaP:Ti was obtained by ion implantation followed by pulsed-laser melting (PLM) using an ArF excimer laser. It was found that PLM energy densities between 0.35 and 0.55 J/cm 2 produced a good recovery of the crystalline structure of GaP (both unimplanted and implanted with Ti), as evidenced by high mobility measured values (close to the reference GaP). Outside this energy density window, the PLM failed to recover the crystalline structure producing a low mobility layer that is electrically isolated from the substrate. Spectral photoconductivity measurements were performed by using the van der Pauw set up. For GaP:Ti a significant enhancement of the conductivity was observed when illuminating the sample with photon energies below 2.26 eV, suggesting that this photoconductivity is related to the presence of Ti in a concentration high enough to form an IB within the GaP bandgap. The position of the IB was estimated to be around 1.1 eV from the conduction band or the valence band of GaP, which would lead to maximum theoretical efficiencies of 25% to 35% for a selective absorption coefficients scenario and higher for an overlapping scenario.

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Results of a gallium phosphide photovoltaic junction with an AR coating under concentration of natural sunlight

Cited by 20 publications

References 7 publications

Photoelectrochemical Behavior of Planar and Microwire‐Array Si|GaP Electrodes

Photoelectrochemical Behavior of Planar and Microwire‐Array Si|GaP Electrodes

Effects of growth temperature and device structure on GaP solar cells grown by molecular beam epitaxy

Strong subbandgap photoconductivity in GaP implanted with Ti

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