Room-temperature 1550-nm lasing from tensile strain N-doped Ge quantum dots on Si

Abstract

N-type heavy doping and tensile strain can significantly improve the luminescence efficiency of Ge materials. The active region of the quantum dot(QD) structure can realize high luminous efficiency due to its 3D carrier confinement. In this study, we constructed a Si-based QD array laser by introducing a 0.25% biaxial tensile strain and $4\times {10}^{19}{\mathrm{cm}}^{-3}$ N type heavy doping to Ge. A band-lifting method was proposed to determine the optimum doping concentration and thus improve the luminescence efficiency of Ge. To obtain accurate characteristics of the laser, we constructed a calculation model of three band transitions and all of the k-space quantum transitions of Ge and other relevant modified models. Results showed that the laser power was $5.31\text{μ}\mathrm{W}$ at a voltage of 2.5 V, and the laser wavelength reached 1519.4 nm at room temperature. The proposed laser can be used as a light source compatible with the Si-based CMOS process.

Keywords:

• Ge quantum dot
• tensile strain
• Si-based light source

Acknowledgments

We thank Huiyun Liu and Junjie Yang of the University College London for valuable help and fruitful discussion. We also thank Yang Sheng for technical help and Hua Zhu for helpful discussions. J. D. Prades acknowledges the support from the Serra Hunter Program, the ICREA Academia Program and Tianjin Distinguished University Professor Program. Hongqiang Li acknowledges the support from Tianjin Talent Special Support Program and Tianjin ‘131’ Innovative Talent Training Program. Correspondence and requests for materials should be addressed to H. Q. Li (email: [email protected]).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

National Natural Science Foundation of China (No. 61675154); Tianjin Key Research and Development Program (No. 19YFZCSY00180); Tianjin Municipal Natural Science Foundation (Nos. 18JCYBJC29100, 18JCQNJC70800); Tianjin Municipal Science and Technology Popularization Program (No. 18KPXMSF00050); Tianjin Major Project for Civil-Military Integration of Science and Technology (No. 18ZXJMTG00260).