UCLA

Integration of arsenide-based III-V compound semiconductors on silicon (Si) has been the focus of significant research to integrate light sources on silicon, enabling an integrated optical solution for chip-chip interconnects in future computing systems, and to make cost-effective and efficient multi-junction solar cells on silicon substrates. The primary obstacle to success is the lattice and thermal expansion mismatches between the semiconductor compounds of interest and the silicon substrates.

In this thesis, a novel heteroepitaxial growth technique, quasi van der Waals epitaxy, promises the ability to grow high quality As-based semiconductor compounds on silicon using a two-dimensional (2D) layered material as a buffer layer, where the van der Waals force is dominant between the layers, thus reducing the strain arising from lattice and thermal expansion coefficient mismatches. The main body of the thesis is structured in three parts. First, theoretical investigations of quasi van der Waals heteroepitaxial growth of arsenide-based III-V compounds on layered materials, such as graphene, Indium Selenide (InSe), Boron Nitride (h-BN) and Molybdenum Selenide (MoS2), where the surface free energy and adsorption energies of Ga, Al, In and As are calculated using DFT calculations. Second, experimental demonstration of a novel low temperature technique for quasi van der Waals heteroepitaxial growth of arsenide based III-V compounds on graphene using Molecular Beam Epitaxy (MBE) is described. Third, using Indium Selenide (InSe) as a buffer layer due to its relatively high surface free energy and stability at high growth temperatures, a high quality and defect-free InGaAs/GaAs double heterostrucure (DH) is integrated onto a GaAs/ Si structure. The crystal quality of GaAs shows the lowest defect density of GaAs grown directly on Si to date, making it a remarkable step toward obtaining optical emitters on silicon substatres. The optical properties of this heterostructure were characterized using micro-photoluminescence (μ-PL), demonstrating room-temperature light emission out of the InGaAs/GaAs heterostructure integrated on thin GaAs on InSe/Si. Planar growth of GaAs thin films on layered materials is a potential route towards heteroepitaxial integration of GaAs on silicon in the developing field of silicon photonics.