Abstract

Integrating semiconductor lasers with silicon (Si) electronics could revolutionize data communication and computing hardware. III-V compound semiconductors are ideal for this but face integration challenges with Si. Methods like micro-transfer printing and flip-chip bonding haven’t achieved wafer-scale integration. Bonding and epitaxial layer lift-off reduce material efficiency and are costly. Direct growth of III-Vs on Si is conceptually simple but faces issues like threading dislocations, lattice, thermal mismatches, and interface problems. Using Ge buffer layers can help, but these require several microns to relax and bury defects. Solid phase epitaxy (SPE) of Si1-xGex layers is a promising alternative but needs further study on strain relaxation and III-V growth mechanisms.

Researchers at McMaster University have developed a novel GaAs/Si1-xGex/Si(111) heterostructure fabrication process. The GaAs epitaxial growth on sub-10-nm-thick strain-relaxed Si1-xGex layers on Si substrates, created through a novel Ge oxidative solid-phase epitaxy process. The relaxation of misfit strain with remarkably thin layers is achieved through a high-temperature solid-phase epitaxy process, which creates a network of dislocations at the Si1-xGex/Si interface. This process also induces composition variations due to a novel defect-enhanced adatom diffusion process. This defect-mediated Ge diffusion in the Si1-xGex film during wet oxidation is unprecedented and currently unreported in the literature. EDS and GPA confirm Si-rich regions matching the periodicity of expected misfit dislocations. The novel method enables fabrication of high-performance GaAs-based lasers and photodetectors on silicon, enhancing efficiency for data communication and optical interconnects. They also facilitate the development of advanced multijunction photovoltaic cells, improving energy conversion rates for residential and commercial solar power systems.

Applications

1. Telecommunications: The integration supports the development of advanced lasers, photodetectors, and modulators, improving data transmission rates and reliability in optical communication networks.
2. Energy: It enables the creation of high efficiency multijunction photovoltaic cells, significantly boosting the performance of solar power systems for residential and commercial use.
3. Computing: The technology facilitates the production of high-speed electronic components, such as transistors, that can be integrated into CMOS circuits, enhancing the performance of computing devices and systems.

Advantages

• Reduced Defect Density
• Strain Relaxation with Thin Layers
• High-Temperature Solid-Phase Epitaxy
• Novel Defect-Enhanced Adatom Diffusion
• Enhanced Device Performance
• Potential for Wafer-Scale Integration.