Er Doped III-Nitride Semiconductors

Abstract

Erbium ions (Er3+) doped in a solid material enables the intra 4f shell transitions from its first excited state (4I13/2) to the ground state (4I15/2). The intra-4f shell transition at 1540 nm is of exceptional interest as the wavelength matches the minimum loss region of silica fibers used in optical communications. Aluminium nitride (AlN) as host material for Erbium (Er) has attracted a lot of interest due to its physical and chemical properties such as the wide bandgap. Metal-Organic Chemical Vapor Deposition (MOCVD) is the most advanced state-of-art growth technique which provides both high quality single crystal thin film deposition capability and high growth rate. MOCVD is a versatile technique that widely used in research laboratories and in industrial factories.

In this thesis, the effects of Er flux on MOCVD grown Er:AlN properties were investigated using different characterization techniques such as X-ray Diffraction (XRD), Photoluminescence (PL) Spectroscopy, Secondary Ion Mass Spectroscopy (SIMS), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM).

XRD θ-2θ scans showed strong peak (002) for AlN and sapphire substrate (Al2O3), and the absence of any secondary phase for all samples. Rocking curve scans showed that increasing the Er flux increases the full width at half maximum (FWHM) of the symmetric (002) planes for AlN:Er. Surface imaging studies showed that increasing Er flux increases the surface roughness. SIMS profiles revealed that Er is uniformly distributed throughout the doped layers and enabled the direct measurement of the doped layer thickness using optical profiler. XPS exhibited the surface quantitative measurement of Aluminium, Nitrogen, Oxygen, and Carbon. PL measurements revealed that increasing the Er flux increases the 1.54μm emission intensity.