中国物理B ›› 2016, Vol. 25 ›› Issue (5): 57804-057804.doi: 10.1088/1674-1056/25/5/057804

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Temperature dependent direct-bandgap light emission and optical gain of Ge

Zhi Liu(刘智), Chao He(何超), Dongliang Zhang(张东亮), Chuanbo Li(李传波), Chunlai Xue(薛春来), Yuhua Zuo(左玉华), Buwen Cheng(成步文)   

  1. State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
  • 收稿日期:2015-12-13 修回日期:2016-01-14 出版日期:2016-05-05 发布日期:2016-05-05
  • 通讯作者: Buwen Cheng E-mail:cbw@semi.ac.cn
  • 基金资助:
    Project supported by the National Basic Research Development Program of China (Grant No. 2013CB632103) and the National Natural Science Foundation of China (Grant Nos. 61377045, 61435013, and 61176013).

Temperature dependent direct-bandgap light emission and optical gain of Ge

Zhi Liu(刘智), Chao He(何超), Dongliang Zhang(张东亮), Chuanbo Li(李传波), Chunlai Xue(薛春来), Yuhua Zuo(左玉华), Buwen Cheng(成步文)   

  1. State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
  • Received:2015-12-13 Revised:2016-01-14 Online:2016-05-05 Published:2016-05-05
  • Contact: Buwen Cheng E-mail:cbw@semi.ac.cn
  • Supported by:
    Project supported by the National Basic Research Development Program of China (Grant No. 2013CB632103) and the National Natural Science Foundation of China (Grant Nos. 61377045, 61435013, and 61176013).

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摘要： Band structure, electron distribution, direct-bandgap light emission, and optical gain of tensile strained, n-doped Ge at different temperatures were calculated. We found that the heating effects not only increase the electron occupancy rate in the Γ valley of Ge by thermal excitation, but also reduce the energy difference between its Γ valley and L valley. However, the light emission enhancement of Ge induced by the heating effects is weakened with increasing tensile strain and n-doping concentration. This phenomenon could be explained by that Ge is more similar to a direct bandgap material under tensile strain and n-doping. The heating effects also increase the optical gain of tensile strained, n-doped Ge at low temperature, but decrease it at high temperature. At high temperature, the hole and electron distributions become more flat, which prevent obtaining higher optical gain. Meanwhile, the heating effects also increase the free-carrier absorption. Therefore, to obtain a higher net maximum gain, the tensile strained, n-doped Ge films on Si should balance the gain increased by the heating effects and the optical loss induced by the free-carrier absorption.

关键词: Ge, light emission, optical gain

Abstract: Band structure, electron distribution, direct-bandgap light emission, and optical gain of tensile strained, n-doped Ge at different temperatures were calculated. We found that the heating effects not only increase the electron occupancy rate in the Γ valley of Ge by thermal excitation, but also reduce the energy difference between its Γ valley and L valley. However, the light emission enhancement of Ge induced by the heating effects is weakened with increasing tensile strain and n-doping concentration. This phenomenon could be explained by that Ge is more similar to a direct bandgap material under tensile strain and n-doping. The heating effects also increase the optical gain of tensile strained, n-doped Ge at low temperature, but decrease it at high temperature. At high temperature, the hole and electron distributions become more flat, which prevent obtaining higher optical gain. Meanwhile, the heating effects also increase the free-carrier absorption. Therefore, to obtain a higher net maximum gain, the tensile strained, n-doped Ge films on Si should balance the gain increased by the heating effects and the optical loss induced by the free-carrier absorption.

Key words: Ge, light emission, optical gain

中图分类号:  (Theory, models, and numerical simulation)

  • 78.20.Bh
78.20.Ci (Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)) 78.55.Ap (Elemental semiconductors)