Photoluminescence quantum efficiency and energy transfer were studied in ErRE (RE = Y, Yb) silicate thin films. For the first time, we experimentally determined the radiative/non-radiative decay rates of ErYb and ErY silicates and obtained photoluminescence quantum efficiencies of 0.28 ± 0.08 and 0.39 ± 0.13, respectively. Energy transfer between Yb and Er in ErYb silicate was investigated by comparing the effective excitation cross sections of ErYb and ErY silicate. At different pumping wavelengths, forward and backward energy transfer caused by the presence of Yb was experimentally demonstrated.

Broadband and anisotropic light emission from rare-earth doped tellurite thin films is demonstrated using Er3+-TeO2 photonic crystals (PhCs). By adjusting the PhC parameters, photoluminescent light can be efficiently coupled into vertical surface emission or lateral waveguide propagation modes. Because of the flexibility of light projection direction, Er3+-TeO2 is a potential broadband light source for integration with three-dimensional photonic circuits and on-chip biochemical sensors.

Silicon nanocrystals (nc-Si), have been shown to act as opto-electronic centers enabling light emission by carrier recombination, when precipitated in a silicon nitride (Si3N4) host. In this work, nc-Si and Germanium nanocrystals (nc-Ge) are studied in sputtered films of Si3N4 and SiGeN for application as tandem cell layers in a Si solar cell. The samples are annealed in a nitrogen gas and forming gas ambient, from 500 ºC to 900 ºC, to investigate the influence of temperature on photoluminescence and photoconductivity.

Sensitization of erbium by ytterbium in Er x Yb 2-x SiO 5 thin films at 980nm optical excitation is demonstrated by means of comparison of the 1.54µm photoluminescence intensities excited with 488nm and 980nm light. Additionally, it is shown that detrimental Er-Er interactions such as concentration quenching increase non-radiative decay rates at high erbium concentrations. Dilution of erbium by ytterbium reduces these interactions, leading to an increase of internal quantum efficiency.

The structural and photoluminescence properties of ytterbium-erbium silicate thin films have been investigated. The films were fabricated by RFmagnetron co-sputtering of Er 2 O 3 , Yb 2 O 3 and SiO 2 on c-Si and subsequent annealing in N 2 or O 2 atmosphere.

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Two dimensional Er 3+ -TeO 2 thin film photonics crystals (PhCs) are fabricated. These PhCs demonstrate broadband enhancement of PL emission at near Infrared (NIR). The PhC structures are written by dual beam focused ion beam (FIB). Highly uniformed patterns with smooth surfaces are observed. A pattern resolution better than hundred nanometers is achieved. PhCs arrays with photonic lattice constants from 350 nm to 1700 nm are examined in order to optimize the PL extraction efficiency. Strong photoluminescence around 1530 nm is observed by 488-532 nm lasers pumping. A confocal microscopy with spectrometer is used to capture the broadband PL signals from individual PhC array.The emission enhancement factor and spectral dependent extraction ratio are analyzed to find the interaction between PL lightwave and PhC structures. By optimize the PhC structures, 1500 um-1560 um broadband PL is successfully converted between the PL emission layer and the external cavity. A 60 % enhancement of surface extraction efficiency is achieved when PhC with periodicity a=800 nm is applied. When photonic lattice constants a are smaller than the critical periodicity 600 nm, the PL light becomes confined inside the thin film layer. Simulation is also performed by two dimensional finite difference time domain (FDTD) calculation in order to explain the experimental observed anisotropic PL enhancements.The broadband PL enhancement enables Er 3+ -TeO 2 PhCs thin film as a potential light source for three dimensional integrated photonic circuits.

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