Thin-film GaAs epitaxial lift-off solar cells for space applications

Schermer, J.J.; Mulder, P.; Bauhuis, G.J.; Larsen, P.K.; Oomen, G.; Bongers, E.

doi:10.1002/pip.616

Cited by 56 publications

(30 citation statements)

References 12 publications

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“…In this way thin, lightweight and flexible solar cells are created, with efficiencies equivalent to or even larger than substrate based solar cells [3,4,5,6]. These characteristics make ELO III-V solar cells excellent candidates for implementation in solar panels for space applications [7]. Due to the additional flexibility new light-weight panel designs become available [8] and the launch costs would be reduced due to the lower weight.…”

Section: Introductionmentioning

confidence: 99%

Effects of copper diffusion in gallium arsenide solar cells for space applications

Leest¹,

Bauhuis²,

Mulder³

et al. 2015

Solar Energy Materials and Solar Cells

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High efficiency, thin-film Epitaxial Lift-Off (ELO) III-V solar cells offer excellent characteristics for implementation in flexible solar panels for space applications. However, the current thin-film ELO solar cell design generally includes a copper handling and support foil. Copper diffusion has a potentially detrimental effect on the device performance and the challenging environment provided by space (high temperatures, electron and proton irradiation) might induce diffusion. It is shown that heat treatments induce copper diffusion. The open-circuit voltage (V oc ) is the most affected solar cell parameter. The decrease in V oc can be explained by enhanced non-radiative recombination via Cu trap levels in the middle of the band gap. The decrease in V oc is found to be dependent on junction depth. In all Cu cells annealed at T ≥ 300 ○ C signs of Cu diffusion are present, which implies that a barrier layer inhibiting Cu diffusion is necessary. Electron radiation damage was found to have no influence on Cu diffusion.

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Section: Introductionmentioning

confidence: 99%

Effects of copper diffusion in gallium arsenide solar cells for space applications

Leest¹,

Bauhuis²,

Mulder³

et al. 2015

Solar Energy Materials and Solar Cells

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“…Over the years this research has yielded significant increases in etch rate, 3,4 an increase in sample size up to 4 inch wafers, 4-6 thin-film GaAs cells with record efficiencies (26.1%), 7 and the demonstration of its potential for space applications. 8 In recent years the importance of the ELO technology for PV applications has received wide-spread attention, resulting in further increase of the thin-film GaAs cell efficiency to 28.3% 9 and industrial interest for genuine thin-film cell production. …”

mentioning

confidence: 99%

Arsenic Formation on GaAs during Etching in HF Solutions: Relevance for the Epitaxial Lift-Off Process

Smeenk¹,

Engel²,

Mulder³

et al. 2012

ECS J. Solid State Sci. Technol.

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The epitaxial lift-off (ELO) process is utilized to produce thin-film III-V devices, while the substrate (GaAs wafer) on which the III-V structure was grown can be reused. However, so far the direct reuse of these GaAs wafers is inhibited by the remnants on the wafer surface that cannot be removed in a straightforward fashion utilizing general cleaning methods. Therefore, etching of GaAs wafers in hydrofluoric acid was investigated by microscopic techniques, profilometry and X-ray photoelectron spectroscopy. It was found that immediately after etching the wafer surface is covered by a brown layer of elemental arsenic. The thickness and uniformity of this layer depend on both illumination during etching and the HF concentration. During storage of the etched wafer the As layer is replaced by As 2 O 3 particles. It is shown that oxide particles form only when the wafer is exposed to light in the presence of air. A model that explains the As formation and the subsequent particle formation is given. © 2012 The Electrochemical Society. [DOI: 10.1149/2.006303jss] All rights reserved. III-V solar cell technology is important in space and concentrated photovoltaic (CPV) applications.1 From a fundamental point of view III-V semiconductors are ideal for solar cell applications. A large range of III-V materials are direct semiconductors allowing for thinfilm cell structures, and III-V compounds can easily be combined into multi-junction cells yielding record efficiencies.2 Present commercially available triple-junction cells for CPV systems reach efficiencies as high as 38%, while current research is aiming to demonstrate efficiencies above 50%.A major disadvantage in the production of high-efficiency III-V solar cells is that they require an expensive single-crystalline GaAs or Ge wafer as a template. After deposition of the solar cell structure the wafer is of no further use for its performance. Nevertheless, using the present fabrication techniques the active thin-film structure including the passive wafer are processed together to a thick solar cell. In order to avoid wasting the substrate, our research group has perfected an epitaxial lift-off (ELO) technique to separate thin-film solar cells from their wafer and transfer them to an inexpensive carrier. The ELO process involves the selective etching of an intermediate AlAs release layer, resulting in thin film cell structures and thus allowing reuse of the wafer. Over the years this research has yielded significant increases in etch rate, 3,4 an increase in sample size up to 4 inch wafers, 4-6 thin-film GaAs cells with record efficiencies (26.1%), 7 and the demonstration of its potential for space applications. 8 In recent years the importance of the ELO technology for PV applications has received wide-spread attention, resulting in further increase of the thin-film GaAs cell efficiency to 28.3% 9 and industrial interest for genuine thin-film cell production. 10-14The aim of ELO is to allow the reuse of the wafer for the production of a large number of thin-film cells ...

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“…Thin-film III-V solar cells obtained by the epitaxial lift-off (ELO) method [1][2][3][4][5][6][7][8][9] offer excellent characteristics for implementation in space solar panels [10][11][12] . However, the harsh space environment (vacuum, UV irradiation, high energy electron and proton irradiation, temperature cycling, etc.)…”

Section: Introductionmentioning

confidence: 99%

Metal diffusion barriers for GaAs solar cells

Leest¹,

Mulder²,

Bauhuis³

et al. 2017

Phys. Chem. Chem. Phys.

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In this study accelerated ageing testing (AAT), J-V characterization and TEM imaging in combination with phase diagram data from literature are used to assess the potential of Ti, Ni, Pd and Pt as diffusion barriers for Au/Cu-based metallization of III-V solar cells. Ni barriers show the largest potential as at an AAT temperature of 250 • C both cells with 10 and 100 nm thick Ni barriers show significantly better performance compared to Au/Cu cells, with the cells with 10 nm Ni barriers even showing virtually no degradation after 7.5 days at 250 • C (equivalent to 10 years at 100 • C at an E a of 0.70 eV). Detailed investigation shows that Ni does not act as a barrier in the classical sense, i.e. preventing diffusion of Cu and Au across the barrier. Instead Ni modifies or slows down the interactions taking place during device degradation and thus effectively acts as an 'interaction' barrier. Different interactions occur at temperatures below and above 250 • C and for thin (10 nm) and thick (100 nm) barriers. The results of this study indicate that 10-100 nm thick Ni intermediate layers in the Cu/Au based metallization of III-V solar cells may be beneficial to improve the device stability upon exposure to elevated temperatures.

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Thin-film GaAs epitaxial lift-off solar cells for space applications

Cited by 56 publications

References 12 publications

Effects of copper diffusion in gallium arsenide solar cells for space applications

Effects of copper diffusion in gallium arsenide solar cells for space applications

Arsenic Formation on GaAs during Etching in HF Solutions: Relevance for the Epitaxial Lift-Off Process

Metal diffusion barriers for GaAs solar cells

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