Open Access Nano Express

Enhanced photoluminescence of multilayer Ge quantum dots on Si(001) substrates by increased overgrowth temperature

Zhi Liu, Buwen Cheng*, Weixuan Hu, Shaojian Su, Chuanbo Li and Qiming Wang

Author affiliations

State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, QingHua East Road, Haidian District, Beijing, 100083, People’s Republic of China

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Citation and License

Nanoscale Research Letters 2012, 7:383  doi:10.1186/1556-276X-7-383

Published: 11 July 2012

Abstract

Four-bilayer Ge quantum dots (QDs) with Si spacers were grown on Si(001) substrates by ultrahigh vacuum chemical vapor deposition. In three samples, all Ge QDs were grown at 520 °C, while Si spacers were grown at various temperatures (520 °C, 550 °C, and 580 °C). Enhancement and redshift of room temperature photoluminescence (PL) were observed from the samples in which Si spacers were grown at a higher temperature. The enhancement of PL is explained by higher effective electrons capturing in the larger size Ge QDs. Quantum confinement of the Ge QDs is responsible for the redshift of PL spectra. The Ge QDs’ size and content were investigated by atomic force microscopy and Raman scattering measurements.

Keywords:
Ge quantum dots; Photoluminescence; Ostwald ripening; Overgrowth temperature