Heteroepitaxy of GaAsP and GaP on GaAs and Si by low pressure hydride vapor phase epitaxy

https://doi.org/10.1016/j.jcrysgro.2020.125623Get rights and content
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Highlights

  • 1.76 eV GaAsP was developed by hydride vapor phase epitaxy for Si based tandem solar cell application.

  • Direct heteroepitaxy of GaAsP on silicon is achieved by hydride vapor phase epitaxy.

  • The threading dislocation density in the GaP heteroepitaxy on GaAs is suppressed by optimizing the GaCl flow.

Abstract

Direct heteroepitaxy of GaAsP and GaP on GaAs and on Si by low-pressure hydride vapor phase epitaxy (HVPE) is investigated as prior studies for photovoltaics and non-linear optics applications. When growing GaAsP on GaAs, it is found that the ambient gas during substrate pre-heating influences the ternary composition as well as the crystalline quality of the subsequent growth. GaAs0.72P0.28 with bandgap energy of 1.76 eV has been achieved, which would be suitable for a top cell in Si tandem solar cell structures. Growth of GaP was investigated on planar GaAs as a prior study for realizing orientation patterned (OP) GaP on OP-GaAs. Threading dislocations caused by the 3.6% lattice mismatch between GaP and GaAs are suppressed by adjusting the GaCl flow, achieving a low full width at half maximum of 146 arcsec for the X-ray diffraction omega scan. Direct heteroepitaxy of GaAsP on Si aiming for achieving a GaAsP/Si dual junction solar cell is demonstrated. The inherent problem of initiating nucleation during the direct heteroepitaxy of III-V on Si by HVPE is overcome by utilizing the vapor mixing approach to grow a low-temperature GaP buffer layer on Si, followed by a GaAsP layer grown by conventional HVPE.

Keywords

A1. Line defects
A3. Hydride vapor phase epitaxy
B2. Semiconducting III-V materials
B2. Nonlinear optic materials
B3. Heterojunction semiconductor devices
B3. Solar cells

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