Abstract

The combination of Si technology for both electronics and active optical components has always attracted a great deal of interest, but so far, the indirect bandgap of this group IV material prevented the fabrication of an efficient light emitter. This obstacle can be circumvented by adopting the concept of the Quantum Cascade Laser (QCL) to the Si/SiGe material system. QCLs rely on intersubband transitions and tunneling, which are not dependent on the type of the bandgap. While the non-polar character of SiGe alloys is an advantage, the large lattice mismatch between Si and Ge, small band offsets in the complex valence band, and large effective masses for holes are severe drawbacks for QCL fabrication.

© 2001 Optical Society of America