Characterization of Ge-on-Si virtual substrates and single junction GaAs solar cells

Ginige, R.; Corbett, Brian; Modreanu, M.; Barrett, Caleb Shuan Chia; Hilgarth, J.; Isella, Giovanni; Chrastina, D.; Känel, H. von

doi:10.1088/0268-1242/21/6/011

Cited by 49 publications

(24 citation statements)

References 21 publications

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“…integration with the existing silicon process technology and it has been a hot research topic for many years. [6][7][8][9] The main problem arises from the 4.2 % lattice mismatch (at 300K) between Ge and Si which ends up in misfit dislocations and other defects (e.g. twins).…”

Section: Introductionmentioning

confidence: 99%

Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

et al. 2014

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International audienceWe report on unusual low temperature (175 °C) heteroepitaxial growth of germanium thin films using a standard radio-frequency plasma process. Spectroscopic ellipsometry and transmission electron microscopy (TEM) reveal a perfect crystalline quality of epitaxial germanium layers on (100) c-Ge wafers. In addition direct germanium crystal growth is achieved on (100) c-Si, despite 4.2% lattice mismatch. Defects rising from Ge/Si interface are mostly located within the first tens of nanometers, and threading dislocation density (TDD) values as low as 106 cm−2 are obtained. Misfit stress is released fast: residual strain of −0.4% is calculated from Moiré pattern analysis. Moreover we demonstrate a striking feature of low temperature plasma epitaxy, namely the fact that crystalline quality improves with thickness without epitaxy breakdown, as shown by TEM and depth profiling of surface TDD

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Section: Introductionmentioning

confidence: 99%

Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

et al. 2014

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“…For these reasons different studies have been carried out to integrate Ge on Si with only a low density of defects in the active region [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Towards III-V solar cells on Si: Improvement in the crystalline quality of Ge-on-Si virtual substrates through low porosity porous silicon buffer layer and annealing

Calabrese¹,

Baricordi²,

Bernardoni³

et al. 2014

AIP Conference Proceedings

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Abstract.A comparison between the crystalline quality of Ge grown on bulk Si and on a low porosity porous Si (pSi) buffer layer using low energy plasma enhanced chemical vapor deposition is reported. Omega/2Theta coupled scans around the Ge and Si (004) diffraction peaks show a reduction of the Ge full-width at half maximum (FWHM) of 22.4% in presence of the pSi buffer layer, indicating it is effective in improving the epilayer crystalline quality. At the same time atomic force microscopy analysis shows an increase in root means square roughness for Ge grown on pSi from 38.5 nm to 48.0 nm, as a consequence of the larger surface roughness of pSi compared to bulk Si. The effect of 20 minutes vacuum annealing at 580°C is also investigated. The annealing leads to a FWHM reduction of 23% for Ge grown on Si and of 36.5% for Ge on pSi, resulting in a FWHM of 101 arcsec in the latter case. At the same time, the RMS roughness is reduced of 8.8% and of 46.5% for Ge grown on bulk Si and on pSi, respectively. The biggest improvement in the crystalline quality of Ge grown on pSi with respect to Ge grown on bulk Si observed after annealing is a consequence of the simultaneous reorganization of the Ge epilayer and the buffer layer driven by energy minimization. A low porosity buffer layer can thus be used for the growth of low defect density Ge on Si virtual substrates for the successive integration of III-V multijunction solar cells on Si. The suggested approach is simple and fast -thus allowing for high throughput-, moreover is cost effective and fully compatible with subsequent wafer processing. Finally it does not introduce new chemicals in the solar cell fabrication process and can be scaled to large area silicon wafers.

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“…Alternatively, Ge virtual substrates were shown to be effective for reducing the TD density. In this work a fully relaxed, approximately one micrometer thick, Ge epitaxial buffer (from now on Geon-Si) is used to accommodate the lattice mismatch between the GaAs layers and the Si substrate (7)(8). Anti-phase domains were effectively eliminated using intentionally misoriented substrates (9).…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Ge-on-Si Substrates for the Integration of High-Quality GaAs Nanostructures on Si

et al. 2013

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Ge-on-Si substrates, made by a thin Ge relaxed layer with a low threading dislocation density and reduced surface roughness deposited on Si, are capable of accommodating the mismatch between GaAs and Si substrate and can be used for the growth of high quality AlGaAs/GaAs layers and of GaAs nanostructures by droplet epitaxy, while maintaining a low thermal budget compatible with the integration of CMOS devices.

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Characterization of Ge-on-Si virtual substrates and single junction GaAs solar cells

Cited by 49 publications

References 21 publications

Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates

Towards III-V solar cells on Si: Improvement in the crystalline quality of Ge-on-Si virtual substrates through low porosity porous silicon buffer layer and annealing

Fabrication of Ge-on-Si Substrates for the Integration of High-Quality GaAs Nanostructures on Si

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