Si-Based Germanium Tin Semiconductor Lasers for Optoelectronic Applications

Student: Sattar Al-Kabi

Degree: Ph.D., August 2017

Major Professor: Dr. Fisher Yu, Dr. Greg Salamo

Research Area(s):

Microelectronics

Photonics

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Background/Relevance

  • Alloying Sn to Ge is a new technique to achieve a group IV direct bandgap material.
  • GeSn is compatible to be integrated with Si based ICs, and  it is good candidate for Si-based lasers.

Innovation

  • Use GeSn material, a new classification of direct bandgap material, as photonic devices such as LEDs and lasers.
  • Monolithic and  direct bandgap of group IV lasers that are compatible with CMOS processes.

Approach

  • Use optical characterizations (PL, Raman, ellipsometry…) to study GeSn to confirm the best material for each application such as lasers.
  • Characterize the laser devices that will be fabricated with different etching methods and depths.
  • Optical pumping study for GeSn edge emitting laser devices using different excited power from several type of lasers.

Key Results

  • Measured PL for different Sn compositions [0 to 17.4%] of Sn with different thickness.
  • Enhancement of the PL intensity for thick films with higher Sn composition ( 8 to 17.4%).
  • Laser was achieved using GeSn as active region with 8 to 17.4% of Sn that cover from 2 to 3 microns with high temperature operation 180 K and lower lasing threshold comparing to what was reported.

Conclusions

  • GeSn alloy is a promising direct bandgap material for photonic devices from group IV.
  • PL measurements shows that GeSn can be reach high Sn% up to 17.4% with high quality of material.
  • The laser is obtained from GeSn cover from 2 to 3 micron with temperature operation up to 180 K and low threshold lasing.

Future Work

  • Design several laser devices with different structures such as QW and DHS for optical and electrical injection lasers.
  • Improve the laser device performance by increasing the temperature operation and reducing the threshold value.
  • Modeling and calculations for laser related parameters, optical gain, modes, efficiency, …etc.