1300-nm InAs/GaAs quantum-dot lasers monolithically grown on Ge and Si substrates for Si photonics

When?

Thursday 2 February 2012, 13:00 to 14:00

Where?

ATI Seminar room - 02ATI02

Open to:

Students, Staff

Speaker:

Dr. Huiyun Liu, University College London

Direct epitaxial growth of III-V materials on Si or Ge is one of the most promising candidates for fabricating light sources on a Si platform. We demonstrated the first room-temperature electronically-pumped 1300-nm InAs/GaAs quantum-dot (QD) lasers epitaxially grown on both Si and Ge substrates. The quality of GaAs buffer layers was first optimized with an aim to minimize the defect density in the III-V buffer, and hence strongest photoluminescence intensity of 1300-nm InAs/GaAs quantum dots. Room-temperature lasing around 1300 nm was demonstrated with threshold current density of 725 A/cm2 for Si-based devices and 55.2 A/cm2 for Ge-based devices.

1300-nm InAs/GaAs quantum-dot laser structures were fabricated by Molecular Beam Epitaxy. The new techniques of III-V buffer layers directly grown on Ge and Si substrates were developed to suppress the formation of threading dislocations and antiphase boundaries. Strong photoluminescence around 1300-nm with linewidth of about 30 meV has been demonstrated for InAs/GaAs QDs grown on both Si and Ge substrates. QD laser structures were optimized on both Si and Ge substrate. For InAs/GaAs QD laser grown on a Si (100) substrate, the first room-temperature electrically-pumped operation at 1302 nm was demonstrated with threshold current density of 725 A/cm2 and output power of ~26 mW for broad-area lasers with as-cleaved facets under pulsed operation. The Si-based InAs/GaAs QD laser has a 42 oC maximum lasing temperature with a characteristic temperature T0 of 44 K. For InAs/GaAs QD laser epitaxially grown on a Ge (100) substrate, lasing at a wavelength of 1.305 μm with the low threshold current density of 55.2 A/cm2 was observed under continuous-wave current drive at room temperature. This is the first III-V QD laser demonstrated on Ge substrate. The QD laser on Ge has a 60 oC maximum lasing temperature for cw operation and 100 oC maximum lasing temperature for pulsed operation.