Optical gain from luminescent a-SiN&lt;inf&gt;x&lt;/inf&gt;O&lt;inf&gt;y&lt;/inf&gt; waveguide

Dong

et al. 2014

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mentioning

confidence: 99%

Higher than 60% internal quantum efficiency of photoluminescence from amorphous silicon oxynitride thin films at wavelength of 470 nm

Dong

et al. 2014

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The role of N-Si-O bonding configurations in tunable photoluminescence of oxygenated amorphous silicon nitride films

Lin

et al. 2015

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Last year, we have reported that the internal quantum efficiency of photoluminescence (PL) from amorphous silicon oxynitride (a-SiNxOy) films has been achieved as high as 60%. The present work intensively investigated the mechanisms for tunable PL in the 2.05–2.95 eV range from our a-SiNx:O films, by using a combination of optical characterizations, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) measurements. The results of XPS, EPR, and photoluminescence excited measurements indicated that the incorporation of oxygen atoms into silicon nitride (a-SiNx) networks not only reduced the band tail structure disorder (Urbach tail width EU) but also created N-Si-O (Nx) defect states in the band gap. We have discovered the distinctive PL characteristics from a-SiNx:O films with various NH3/SiH4 ratios. The PL peak energy (EPL) is independent of the excitation energy (Eexc) and the PL intensity (IPL) is regardless of the optical band gap (Eopt) but is proportional to the Nx defects concentration, both of which are completely different from the PL characteristics by band tail states recombination mechanism, in which the EPL is proportional to Eexc (when Eexc ≤ Eopt) and the IPL is dependent on the relative position of Eexc and Eopt. Based on the N-Si-O bonding configurations and the distinctive PL characteristics, the radiative recombination mechanism through the N-Si-O defect states has been proposed, by which the performance of stimulated emission may be realized in this kind of a-SiNx:O films.

Dynamics of high quantum efficiency photoluminescence from N-Si-O bonding states in oxygenated amorphous silicon nitride films

Lin

et al. 2016

We have reported high internal quantum efficiency (IQE) (∼60%) of photoluminescence (PL) at 470 nm wavelength from oxygenated amorphous silicon nitride (a-SiNx:O) films. In this work, we explored the dynamics of high PL IQE from luminescent N-Si-O bonding states in a-SiNx:O films by using a combination of time resolved PL (TRPL) and temperature dependent PL (TDPL) measurements. The TRPL measurements include time integrated PL, microsecond range PL, and nanosecond range PL measurement modes. The a-SiNx:O films exhibit ns PL decay dynamics that is independent of pumping fluence (WPF) and uniform across the PL spectrum, which is different from the PL decay behavior in a-SiNx films. Particularly, we precisely monitored the temporal evolution of the PL spectra profile to verify that the luminescent N-Si-O bonding states are responsible for the observed blue PL with a radiative recombination rate of ∼108 s−1. Such very fast radiative recombination rate can be compared with that in direct band gap CdSe nanocrystals and can also help us to understand the high PL IQE in a-SiNx:O films. Moreover, by combining the TD-PL lifetimes with the PL IQE values, the temperature dependence of radiative and nonradiative lifetime can be determined.