Multi-technique characterisation of MOVPE-grown GaAs on Si

Abstract

The heterogeneous integration of III-V materials on a Si CMOS platform offers tremendous prospects for future high speed and low power logic applications. That said this integration generates immense scientific and technological challenges. In this work multi-technique characterisation is used to investigate properties of GaAs layers grown by Metal-Organic Vapour Phase Epitaxy (MOVPE) on Si substrates -(100) with 4: offset towards <110> -under various growth conditions. This being a crucial first step towards the production of III-V template layers with a relatively lower density of defects for selective epitaxial overgrowth of device quality material. The optical and structural properties of heteroepitaxial GaAs are first investigated by micro-Raman spectroscopy and photoluminescence and reflectance measurements. High-resolution X-ray diffraction (HR-XRD) is used to investigate structural properties. Advanced XRD techniques, including double-axis diffraction and X-ray crystallographic mapping are used to evaluate degrees of relaxation and distribution of the grain orientations in the epilayers, respectively. Results obtained from the different methodologies are compared in an attempt to understand growth kinetics of the materials system. The GaAs overlayer grown with annealing at 735:C following As predeposition at 500:C shows the best crystallinity. Close inspection confirms the growth of epitaxial GaAs preferentially oriented along (100) embedded in a highly-textured polycrystalline structure.

Structural and optical characterization of GaAs nano-crystals selectively grown on Si nano-tips by MOVPE

“…Interestingly, figure 5(a) reveals an additional peak close to the GaAs TO signal at smaller wavenumbers. Most likely, this Raman signal is due to As crystallites stemming from the long As-annealing times prior to the GaAs deposition [30].…”