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Light Emission From Silicon

Light Emission From Silicon. Outline. Introduction Some background Information Why Silicon? Introduce a structure Ge -on-Si Light-Emitting Materials and Devices for Silicon Photonics References. Introduction. What is Band gap? What is direct and indirect Band gap ?. Introduction.

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Light Emission From Silicon

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  1. Light Emission From Silicon

  2. Outline • Introduction • Some background Information • Why Silicon? • Introduce a structure • Ge-on-Si Light-Emitting Materials and Devices for Silicon Photonics • References

  3. Introduction • What is Band gap? • What is direct and indirect Band gap ?

  4. Introduction

  5. Why Silicon? Using silicon allows us to Integrate photonics and microelectronics , and to exploit existing processing technology and know-how . Most of the components required for silicon photonics exist, but the missing link is a silicon-based optical source. Our work focuses on filling this gap. Silicon is a very inefficient light emitter, thanks to its indirect band gap. This requires us to develop techniques to modify its optical and electronic properties.

  6. Introduce a structure Quantum Confinement Efficiency > 10 %

  7. Ge-on-Si Light-Emitting Materials and Devices for Silicon Photonics • Theory • Ge-on-Si is a particularly interesting candidate due to its pseudo direct band gap behavior and its compatibility with advanced electronics on Si. • The direct band gap of Ge is 0.8 eV, corresponding exactly to 1550 nm. • Tensile strain further decreases the energy difference between Γ and L valleys so that Ge becomes closer to a direct band gap material (Fig. 1b)

  8. Ge-on-Si Light-Emitting Materials and Devices for Silicon Photonics • Tensile strained epitaxial Ge was grown on Si by ultra-high vacuum chemical vapor deposition (UHVCVD) .

  9. Ge-on-Si Light-Emitting Materials and Devices for Silicon Photonics • Although theory predicts that Ge becomes a direct band gap material under 2% tensile strain, the band gap shrinks to only 0.5 eV and the emission wavelength shifts to 2500 nm. • To obtain direct band gap emission while still keeping the wavelength around 1550 nm, we proposed a combination of two approaches, as shown in Fig. 1c. • introducing 0.25% tensile strain to decrease the difference between the direct and indirect gaps of Ge . • compensating the remaining energy difference between Γ and L valleys by n-type doping such that the Fermi level reaches the Γ valley .

  10. References [1] : Dr.hasankatuzian, Photonic Vol-1 [2] : Dr.hasankatuzian, Photonic Vol-2 [3] : Jifeng Liu , Towards a Ge-based Laser for CMOS Applications [4] : Xiaochen Sun , Ge-on-Si Light-Emitting Materials and Devices for Silicon Photonics

  11. Thanks for your patience

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