All-MBE grown InAs/GaAs quantum dot lasers with thin Ge buffer layer on Si substrates

A high-performance III-V quantum-dot (QD) laser monolithically grown on Si is one of the most promising candidates for commercially viable Si-based lasers. Great efforts have been made to overcome the challenges due to the heteroepitaxial growth, including threading dislocations and anti-phase boundaries, by growing a more than 2 mu m thick III-V buffer layer. However, this relatively thick III-V buffer layer causes the formation of thermal cracks in III-V epi-layers, and hence a low yield of Si-based optoelectronic devices. In this paper, we demonstrate a usage of thin Ge buffer layer to replace the initial part of GaAs buffer layer on Si to reduce the overall thickness of the structure, while maintaining a low density of defects in III-V layers and hence the performance of the InAs/GaAs QD laser. A very high operating temperature of 130 degrees C has been demonstrated for an InAs/GaAs QD laser by this approach.