Fig. 1. (Color online) (a) The plot of bandgap energy and wavelength versus lattice constant and misfit between III–V and group IV ^[20]. The electron and hole mobilities in units of cm²/(V·s) are also shown below the chemical symbols. (b) Cross-sectional TEM image on the interface between GaAs and silicon.

Fig. 2. (Color online) (a) Schematic showing polar/nonpolar interface between GaAs and Ge. Mono-atomic steps on Ge surface result in APBs, planes of As–As or Ga–Ga bonds. The antiphase domains (APBs) can also self-annihilate (left) or rise to the epi-layer surface (right). Diatomic steps on the Ge surface (center) do not result in APB formation^[25]. (b) Surface AFM image of GaAs grown on Si (001) substrate, which indicates a high density of APBs.

Fig. 3. Optical microscope image of the thermal cracks on III–V/Si surface.

Fig. 4. (Color online) (a) 5 × 5 μm² AFM image of 250 nm GaAs buffer layer epitaxial growth on Ge substrate. (b) Cross-sectional TEM image at the interface of GaAs and Ge.

Fig. 5. (Color online) (a) The schematic of 5-layer InAs/GaAs QD structure grown on Ge substrate for O-band wavelength emission. (b) RT PL spectra of InAs/GaAs QDs on GaAs/Ge substrate and GaAs substrate, respectively. Inset: Zoomed-in cross-sectional TEM image of InAs/GaAs QDs on GaAs/Ge substrate.

Fig. 6. (Color online) (a) 5 × 5 μm² AFM image of InGaAs metamorphic buffer layer epitaxially grown on GaAs/Ge substrate. (b) The cross-sectional TEM image of the epitaxial structures on Ge. The arrow shows the growth direction. (c) High-magnification TEM image of a truncated InAs/InGaAs QD. (d) RT PL spectra of InAs/InGaAs QDs grown on both Ge substrate and GaAs substrate. Inset: 1 × 1 μm² AFM image of InAs QDs on Ge substrate.

Fig. 7. (Color online) (a), (b) and (c) Cross-sectional SEM images of U-shape patterned Si substrate, homoepitaxy of 550 nm Si on (111)-faceted Si hollow substrate, and III–V buffer layers on (111)-faceted Si hollow substrate, respectively. All the images are taken along the [110] axis. (d) 10 × 10 μm² AFM image of III–V buffer layers on Si substrate.

Fig. 8. (Color online) (a) Cross-sectional TEM image of GaAs on (111)-faceted Si hollow substrate, taken along [110] axis. (b) Plan-view ECCI to show TDs on GaAs/Si template. (c) Plan-view TEM image of GaAs surface on Si.

Fig. 9. (Color online) (a) RT PL spectra of InAs/GaAs QDs grown on both GaAs and GaAs/Si (001) substrates, for O-band emission. Inset: 1 × 1 μm² AFM image of InAs/GaAs QDs on GaAs/Si substrate. (b) RT PL spectra of InAs/InGaAs QDs grown on both GaAs and GaAs/Si (001) substrates, for C/L-band emission. Inset: 1 × 1 μm² AFM image of surface InAs/InGaAs QDs on GaAs/Si substrate.

Fig. 10. (Color online) Schematic diagrams of (a) microdisk laser structure and (b) microdisk laser on GaAs/Si (001) substrate. (c) and (d) Tilted SEM images of microdisk lasers on GaAs (001) and GaAs/Si (001) substrates, respectively.

Fig. 11. (Color online) Integrated intensity of microdisk lasers versus the power of pump laser on (a) GaAs substrate and (c) Si (001) substrate, respectively. Inset: the log–log plot of ‘L–L curve’. PL spectra of microdisk lasers on (b) GaAs substrate and (d) Si (001) substrate, respectively, under different pump powers.