GaAsP/Si tandem solar cells: In situ study on GaP/Si:As virtual substrate preparation

Paszuk, Agnieszka; Supplie, Oliver; Kim, Boram; Brückner, Sebastian; Nandy, Manali; Heinisch, Alexander; Kleinschmidt, Peter; Nakano, Yoshiaki; Sugiyama, Masakazu; Hannappel, Thomas

doi:10.1016/j.solmat.2017.07.032

Cited by 13 publications

(6 citation statements)

References 40 publications

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“…These results (i.e., presence of oxygen in the interface of Sample 1, whose pre-exposure has the lowest temperature) supports the idea that the temperature plays a role on the deoxidation step [39], [44]. This agrees with previous results [27] in which the effectiveness of AsH 3 in removing oxygen from the surface at temperatures higher than 700 • C was observed by Auger Electron Spectroscopy.…”

Section: Resultssupporting

confidence: 91%

Advanced Transmission Electron Microscopy Investigation of Defect Formation in Movpe-Growth of Gap on Silicon Using Arsenic Initial Coverage

Navarro

García‐Tabarés

Ramasse³

et al. 2022

SSRN Journal

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Section: Resultssupporting

confidence: 91%

Advanced Transmission Electron Microscopy Investigation of Defect Formation in Movpe-Growth of Gap on Silicon Using Arsenic Initial Coverage

Navarro

García‐Tabarés

Ramasse³

et al. 2022

SSRN Journal

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“…Afterwards, the wafers are exposed to a short flux of AsH 3 (Figure 2d). This so-called pre-exposure step aids in the deoxidation and the elimination of other contaminants as carbon [18][19][20]. In principle, such group-V pre-exposure could be also interesting in order to form a p-n junction for the bottom subcell by the in-diffusion of As into the wafer.…”

Section: Process Rationalementioning

confidence: 99%

Growth of GaP Layers on Si Substrates in a Standard MOVPE Reactor for Multijunction Solar Cells

et al. 2021

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Gallium phosphide (GaP) is an ideal candidate to implement a III-V nucleation layer on a silicon substrate. The optimization of this nucleation has been pursued for decades, since it can form a virtual substrate to grow monolithically III-V devices. In this work we present a GaP nucleation approach using a standard MOVPE reactor with regular precursors. This design simplifies the epitaxial growth in comparison to other routines reported, making the manufacturing process converge to an industrial scale. In short, our approach intends to mimic what is done to grow multijunction solar cells on Ge by MOVPE, namely, to develop a growth process that uses a single reactor to manufacture the complete III-V structure, at common MOVPE process temperatures, using conventional precursors. Here, we present the different steps in such GaP nucleation routine, which include the substrate preparation, the nucleation itself and the creation of a p-n junction for a Si bottom cell. The morphological and structural measurements have been made with AFM, SEM, TEM and Raman spectroscopy. These results show a promising surface for subsequent III-V growth with limited roughness and high crystallographic quality. For its part, the electrical characterization reveals that the routine has also formed a p-n junction that can serve as bottom subcell for the multijunction solar cell.

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“…Si(100) wafers with 2° offcut toward [011] were thermally deoxidized at 1000 °C and 950 mbar . The arsenic-modified, double-layer stepped surface was prepared by annealing the surfaces under the tertiarybutylarsine precursor at 830 °C. ,, Triethylgallium (TEGa), trimethylaluminum (TMAl), and tertiarybutylphosphine (TBP) were used as the precursors for the growth of GaP or GaP/AlP NLs at 420 °C and the subsequent GaP buffer layer growth at 595 °C. The GaP nucleation consisted of 10 alternating precursor pulses each of TBP and TEGa (1 s each with 1 s pause in between) .…”

Section: Experimental and Analysis Methodsmentioning

confidence: 99%

“…Defects in the GaP epilayer related to the polar-on-nonpolar epitaxy, the so called antiphase domains, can be avoided by preparing the Si(100) substrates with a double-layer stepped surface. − In order to avoid defects such as stacking faults (SFs), which are errors in the stacking of the atomic planes, and stacking fault pyramids (SFPs), which are composed of four intersecting SFs, the process route of the GaP nucleation and growth must be precisely controlled . Adequate preparation of the Si(100) surface for obtaining antiphase domain-free GaP buffer layers has been shown on Si substrates with various offcut angles (from almost exactly oriented to vicinal substrates) in MOCVD reactors, which contain III–V residuals. , A commonly applied, two-step GaP growth procedure, which should ensure two-dimensional growth with a low density of SFs and SFPs, includes a nucleation step at a low temperature of around 420 °C, followed by the growth at an increased temperature of around 600 °C. ,, It has been shown that the SFs can be formed upon coalescence of GaP islands formed at an early stage during epitaxial growth on Si substrates. , Thus, a smooth GaP/Si heterointerface, which is free of three-dimensional islands, appears highly beneficial.…”

Section: Introductionmentioning

confidence: 99%

A Route to Obtaining Low-Defect III–V Epilayers on Si(100) Utilizing MOCVD

Nandy

Paszuk

Feifel

et al. 2021

Crystal Growth & Design

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Low-defect III−V multilayer structures grown on Si(100) open opportunities for a wide range of cost-effective high-performance photovoltaic and optoelectronic devices. For that, (Al)GaP epilayers prepared almost lattice-matched on Si(100) substrates can serve as high-quality virtual substrates for subsequent heteroepitaxial growth. The evolution of crystal defects, such as stacking fault pyramids or threading dislocations, needs to be impeded already during the first preparation step, the III−V-on-Si nucleation, as they tend to propagate into the subsequently grown layers and increase nonradiative electron−hole recombination rates, which finally degrade the device performance. We establish a ternary GaP/AlP pulsed nucleation process on Si(100) substrates fabricated by metalorganic chemical vapor deposition, and compare it to the defect evolution from pure GaP nucleation layers (NLs). The entire procedure was optically monitored in situ using reflection anisotropy spectroscopy. Crystal defects were investigated by electron channeling contrast imaging. GaP grown on GaP/ AlP NLs exhibits drastically reduced densities of threading dislocations and stacking faults by 1 and 2 orders of magnitude, respectively, compared to buffer layers grown on binary GaP NLs. We observed that the surface morphology at the initial stage of growth of these buffer layers is significantly smoother compared to the buffer layers grown on pure GaP NLs using atomic force microscopy. The proposed nucleation procedure here is supposed to substantially improve the crystalline quality of III−V buffer layers integrated on Si(100) wafers.

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GaAsP/Si tandem solar cells: In situ study on GaP/Si:As virtual substrate preparation

Cited by 13 publications

References 40 publications

Advanced Transmission Electron Microscopy Investigation of Defect Formation in Movpe-Growth of Gap on Silicon Using Arsenic Initial Coverage

Advanced Transmission Electron Microscopy Investigation of Defect Formation in Movpe-Growth of Gap on Silicon Using Arsenic Initial Coverage

Growth of GaP Layers on Si Substrates in a Standard MOVPE Reactor for Multijunction Solar Cells

A Route to Obtaining Low-Defect III–V Epilayers on Si(100) Utilizing MOCVD

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