Enhancement of bulklike second-order nonlinear susceptibility in SiGe/Si step wells and biasing-field controlled (Si5Ge5)100 superlattices

Xinhui Zhang, Zhenghao Chen, Linzhen Xuan, Shaohua Pan, and Guozhen Yang
Phys. Rev. B 56, 15842 – Published 15 December 1997
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Abstract

Second-harmonic generation (SHG) from electric-field biased (Si5Ge5)100 superlattices and Si0.75Ge0.25/Si0.57Ge0.43/Si step asymmetry wells were studied. Contributions from the different sources to second-order susceptibility χ(2) were systematically analyzed for these two kinds of asymmetry Si/Ge quantum-well structures. The bulklike χ(2) was large enough to be observed while the strain-induced contribution to χ(2) was relatively small for (Si5Ge5)100 superlattices under an applied field of 100 kV/cm. However, strain-enhanced effects were large compared to the contribution from the bulk for the optical χ(2) in SiGe/Si step wells. The results show that different asymmetric structures have different contributional distributions of SHG sources. The peak value of χ(2) was as large as 5×106esu for a (Si5Ge5)100 superlattice under 100 kV/cm electric field and 0.6×106esu for SiGe/Si step wells. These large bulklike χ(2) values indicate that Si/Ge quantum wells with asymmetric structures have potential applications to optoelectronic materials and devices with the existing Si-based technology.

  • Received 14 May 1997

DOI:https://doi.org/10.1103/PhysRevB.56.15842

©1997 American Physical Society

Authors & Affiliations

Xinhui Zhang, Zhenghao Chen, Linzhen Xuan, Shaohua Pan, and Guozhen Yang

  • Laboratory of Optical Physics, Institute of Physics & Center for Condensed Matter Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing 100080, People’s Republic of China

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Vol. 56, Iss. 24 — 15 December 1997

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