Abstract
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 µm 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 °C has been demonstrated for an InAs/GaAs QD laser by this approach.
Highlights
A TD density (TDD) of ∼6 × 108 cm−2 is obtained after the growth of this 300 nm Ge layer, which is similar to TDD level after the first dislocation filter layers (DFLs) for GaAs monolithically grown on Si [17, 39]
Since Ge has an almost identical lattice constant to GaAs, a very limited number of misfit dislocations is introduced during the epitaxy of GaAs on Ge, leading to few additional threading dislocations (TDs) propagating towards DFLs
A final TDD of 4 × 106 cm−2 is obtained after the four sets of DFLs, as indicated in the Electron channelling contrast imaging (ECCI) image shown in figure 2(c)
Summary
The large lattice mismatch, incompatible thermal expansion coefficients and different symmetry between Si and the III–V materials lead to the generation of threading dislocations (TDs), thermal cracks and anti-phase boundaries (APBs), respectively [19,20,21,22,23,24] All these defects generate non-radiative recombination centres, and dramatically hinder the laser performance in terms of operating temperature, output power and reliability [24, 25]. Developing an InAs/GaAs QD laser device monolithically grown on a Ge/Si virtual substrate (VS) has achieved remarkable progresses [37, 38], but all high-quality Ge/Si VSs were manufactured by metal-organic chemical vapour deposition system and transferred into molecular beam epitaxy (MBE) system for further laser structure epitaxy. Lasing was observed up to 130 ◦C under pulsed operation for InAs/GaAs QD lasers grown on a Ge/Si VS by using this unique twin MBE system
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
