14. III–V Quantum-Dot Materials and Devices Monolithically Grown on Si Substrates

The integration of III–V photonics materials and devices with Si microelectronics will enable the fabrication of complex optoelectronic circuits, which will permit the creation of the long-dreamed chip-to-chip and system-to-system optical communications. Direct epitaxial growth of semiconductor III–V compounds on Si substrates is one of the most promising candidates for the fabrication of photonics devices on the Si platform. III–V quantum dots (QDs) offer an attractive alternative to conventional quantum wells(QWs) for building III–V lasing devices on a Si platform due to their unique advantages. We developed the long-wavelength InAs/GaAs QD materials and devices monolithically grown on Si, Ge, and Ge-on-Si substrates by the use of Molecular Beam Epitaxy. Room-temperature(RT) lasing at a wavelength of around 1.3 \(\upmu \)m has been achieved with threshold current densities of 64.3 A/cm\(^{2}\) and lasing operation up to 83\(\,^{\circ }\mathrm{{C}}\) for Si-based ridge-waveguide InAs/GaAs QD lasers with as-cleaved facets. The optical and electrical properties of InAs/GaAs QDs grown on Si substrates were further investigated to evaluate the potential for Si-based photodiodes. A peak responsivity of 5 mA/W was observed at 1.28 \(\upmu \)m, while the dark current was two orders of magnitude lower than those reported for Ge-on-Si photodiodes. These studies ultimately form the basis for the monolithic integration of 1.3-\(\upmu \)m InAs/GaAs QD lasers and detectors on the Si platform.