Epitaxial III-V on silicon-on-insulator platforms for photonic integration

Ratiu, Bogdan-Petrin 2023. Epitaxial III-V on silicon-on-insulator platforms for photonic integration. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

An epitaxially integrated laser has long been considered a holy grail of silicon photonics as it is the last piece of the fabrication process to be fully integrated on-chip. This thesis studies three different approaches to move past the physical constraints imposed by growing mismatched crystals, each with their own advantages and application potential. The first approach uses defect filter layers and quantum dots as defect-resistant gain material to minimise the effects of threading dislocations. Using a novel InAsP/InP thick defect filter layer on silicon we achieve a threading dislocation density of 7.3 × 10^7cm−2 using a buffer under 2 μm thick. To improve the gain and uniformity of quantum dots on InP, a desorption step is performed by stopping the arsenic flow during the growth interruption. The second approach uses inherently threading dislocation free InGaAs nanowires on silicon to create surface emitting photonic crystal lasers. By deforming a honeycomb lattice, flat band edge emission at the Γ point is achieved with a very low threshold of 1.25 μJ cm−2. Curved photonic crystal cavities are also demonstrated for the first time, showing independence of bending radius due to whispering gallery modes. The third approach, tunnel epitaxy, is used to create planar, defect-free III-V slabs on silicon and SOI. By using aspect ratio trapping and changing the growth direction from vertical to horizontal we are able to grow 3×250 μm GaAs slabs. In-plane and crosssectional TEM and room-temperature PL analysis are used to study the defect trapping mechanism and strain relaxation.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	MOCVD, epitaxy, heteroepitaxy, silicon-on-insulator, threading dislocations, lasers, silicon photonics, III-V
Funders:	EPSRC
Date of First Compliant Deposit:	19 June 2024
Last Modified:	24 Jun 2024 11:45
URI:	https://orca.cardiff.ac.uk/id/eprint/169919

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