Real-Time Structural Analysis of Compositionally Graded InGaAs/GaAs(0 0 1) Layers

Author

Sasaki, Takuo ; Suzuki, Hidetoshi ; Inagaki, Makoto ; Ikeda, Kazuma ; Shimomura, Kenichi ; Takahasi, Masamitu ; Kozu, Miwa ; Hu, Wen ; Kamiya, Itaru ; Ohshita, Yoshio ; Yamaguchi, Masafumi

Author_Institution

Toyota Technol. Inst., Nagoya, Japan

Volume

2

Issue

1

fYear

2012

Firstpage

35

Lastpage

40

Abstract

Compositionally step-graded InGaAs/GaAs(0 0 1) buffers with overshooting (OS) layers were evaluated by several characterization techniques for higher efficiency metamorphic III-V multijunction solar cells. By high-resolution X-ray diffraction, we found that fully relaxed or tensile strained top layers can be obtained by choosing appropriate OS layer thickness. Moreover, from real-time structural analysis using in situ X-ray reciprocal space mapping (in situ RSM), it was proved that the top layer is almost strained to the OS layers, and it is independent of the thicknesses of the OS layers. Dislocations in the vicinity of the OS layers were observed by transmission electron microscopy, and the validity of results of in situ RSM was confirmed from the viewpoint of misfit dislocation behavior. Finally, by photoluminescence measurements, we showed that tensile strained top layers may be suitable for the improvement of minority-carrier lifetime.

Keywords

III-V semiconductors; X-ray diffraction; carrier lifetime; dislocations; gallium arsenide; indium compounds; interface structure; minority carriers; photoluminescence; transmission electron microscopy; InGaAs-GaAs; X-ray reciprocal space mapping; compositionally graded layers; high-resolution X-ray diffraction; metamorphic multifunction solar cells; minority-carrier lifetime; misfit dislocation; photoluminescence; real-time structural analysis; strain relaxation; transmission electron microscopy; Gallium arsenide; Indium; Lattices; Photovoltaic cells; Real time systems; Strain; X-ray scattering; Compositionally graded buffers; lattice-mismatched heteroepitaxy; metamorphic multijunction solar cells; real-time analysis;

fLanguage

English

Journal_Title

Photovoltaics, IEEE Journal of

Publisher

ieee

ISSN

2156-3381

Type

jour

DOI

10.1109/JPHOTOV.2011.2174198

Filename

6087260