Monolithic GeSn Light-Emitter on Si for Integrated Photonic Circuits

Student: Yiyin Zhou

Degree: Ph.D., May 2020

Major Professor: Dr. Fisher Yu

Microelectronics

Photonics

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Background/Relevance

  • Si photonics plays great role in applications such as data communication and optical sensing.
  • Efficient light-emitting source monolithically on Si is missing.   Monolithic integration of light source on Si would make the Si photonics more cost-effective, compact, and reliable.

Innovation

  • Low-cost light source on Si meets the need of light source  integration for Si photonics.
  • Tunable light emission wavelength from near- to mid-infrared enables a wide range of applications.

Approach

  • Device simulation was performed by using MATLAB, TCAD, FDTD simulation software.
  • Epitaxial growth using commercial RP-CVD under CMOS compatible temperatures.
  • Material characterization using techniques such as PL, Raman, Ellipsometry, XRD, SIMS, TEM, and etc.
  • LED and laser devices fabrication using standard fabrication process.
  • Device was tested at cryogenic temperatures.

Key Results

  • On Si direct band gap GeSn LEDs were achieved with peak power of ~ 50 µW.
  • Optical pumped GeSn bulk Laser was achieved at 270 K.
  • Optical pumped multiple quantum laser was studied with low threshold at 25 kW/cm2.
  • Electrically pumped GeSn laser has been firstly demonstrated!

Conclusions

  • Material characterizations resolves the information strain, band gap energy, and defect density.
  • Optically pumped lasers was demonstrated with a near room-temperature operation and reduced threshold at low temperature.
  • LED designs enables the study the diode device performance.
  • Electrically pumped lasers were demonstrated with maximum temperature potation at 100 K and threshold density of ~3kA/cm2.

Future Work

  • Optimize the device structures for higher performance in efficiency and maximum operating temperature.