Jae Hyung Yi

Light emission from silicon-rich nitride nanostructures

Light-emitting Si-rich silicon nitride (SRN) films were fabricated by plasma enhanced chemical vapor deposition followed by low temperature (500–900°C) annealing. The optical properties of SRN films were studied by micro-Raman and photoluminescence spectroscopy and indicate the presence of small Si clusters characterized by broad near-infrared emission, large absorption/emission Stokes shift, and nanosecond recombination. Our results are supported by first-principles simulations indicating that N atoms bonded to the surface of nanometer Si clusters play a crucial role in the emission mechanism of SRN films. Light emission from SRN systems can provide alternative routes towards the fabrication of optically active Si devices.

Light emission efficiency and dynamics in silicon-rich silicon nitride films

Light-emitting Si-rich silicon nitride (SRN) films were fabricated by plasma enhanced chemical vapor deposition followed by thermal annealing and the SRN external quantum efficiency was measured. The SRN light emission temperature dependence and recombination dynamics were also studied. Small emission thermal quenching from 4 to 330 K with wavelength dependent, nanosecond recombination lifetime was observed. Light emission from SRN systems can provide alternative routes towards the fabrication of efficient Si-based optical devices.

Spectrally enhanced light emission from aperiodic photonic structures

Light-emitting silicon-rich, SiNx∕SiO2 Thue-Morse (T-M) multilayer structures have been fabricated in order to investigate the generation and transmission of light in strongly aperiodic deterministic dielectrics. Photoluminescence and optical transmission data experimentally demonstrate the presence of emission enhancement effects occurring at wavelengths corresponding to multiple T-M resonance states. Emission enhancement effects by a factor of almost 6 with respect to homogeneous SiNx dielectrics have been experimentally measured, in good agreement with transfer matrix simulations. The unprecedented degree of structural flexibility of T-M systems can provide alternative routes towards the fabrication of optically active multiwavelength photonic devices.

Light-Emitting Silicon Nanocrystals and Photonic Structures in Silicon Nitride

In this paper, we review our main results on the optical and electrical properties of light-emitting silicon nanocrystals (Si-ncs) obtained from the thermally induced nucleation in amorphous silicon-rich nitride (SRN) films deposited either by plasma-enhanced chemical vapor deposition (PE-CVD) or magnetron sputtering. In particular, we discuss the Si-ncs microscopic light emission mechanism combining the optical data with the first-principle calculations of the absorption/emission Stokes shifts and recombination lifetimes. In addition, we report on the electrical injection characteristics of simple p-i-n device structures showing efficient bipolar transport and room temperature electroluminescence, and demonstrate efficient energy sensitization of erbium (Er) ions from the Si-ncs embedded in the SRN matrices. We further show that the light-emitting nanocrystals in SRN can be embedded in aperiodic photonic environments, where the localized optical modes can be used to significantly enhance the Si-ncs emission intensity at different emission wavelengths. These results suggest that the Si-ncs embedded in the SRN matrices have a large potential for the fabrication of optically active photonic devices based on the Si technology

Synthesis, Characterization, and Modeling of Nitrogen-Passivated Colloidal and Thin Film Silicon Nanocrystals

We review our main experimental and theoretical results on the optical emission properties of Si-nanocrystals (Si-ncs) fabricated by colloidal and thin film deposition techniques, showing that the surface chemistry of the Si-ncs or the surrounding matrix play a crucial role in determining both the structural stability and the optoelectronic properties of Si-nc. Our results, guided by first-principles simulations indicate that nitrogen, oxygen, and carbon atoms bonded to the surface of nanometer silicon clusters play a crucial role in the emission mechanism of small Si quantum dots. The control and the understanding of the Si-nc surface structure and composition can provide alternative routes toward the fabrication of optically active complementary metal/oxide semiconductor devices

Light-emitting silicon-rich nitride systems and photonic structures

In this paper we report recent results on the optoelectronic properties of silicon-rich nitride (SRN), a novel material for microphotonics applications compatible with silicon technology. We have investigated optical emission, energy transfer phenomena to erbium ions and PbS colloidal quantum dots in SRN films and grown active photonic SRN structures. The optical properties of the films were studied by micro-Raman and photoluminescence spectroscopy and, as confirmed by transmission electron microscopy analysis, indicate the presence of small (1–2 nm) Si clusters characterized by efficient (7% quantum efficiency at room temperature), broad-band and near-infrared emission with very large absorption/emission Stokes shift. Time and temperature resolved photoluminescence measurements demonstrate nanosecond-fast, wavelength-dependent recombination dynamics with negligible light emission thermal quenching from 4 to 330 K. First-principles simulations of 1 nm size crystalline and amorphous silicon dots show that nitrogen atoms bonded to the surface of nanometre silicon clusters play a crucial role in the emission mechanism of SRN films. In addition, we show that SRN is a suitable material for the fabrication of light-emitting complex photonic crystals and novel waveguide structures based on resonant transmission of localized light states in aperiodic dielectrics. The versatility of light-emitting SRN systems can provide alternative routes towards the fabrication of optically active CMOS devices.

Si-Rich Dielectrics for Active Photonic Devices

The quest to develop an efficient Si-based light emitter has stimulated research worldwide. Among the several approaches being considered, enhancing the probability of light emission through the use of Si nanocrystals embedded in SiO2 shows considerable promise due to the demonstration of efficient room temperature light emission and optical gain. In this chapter, we compare the nucleation, light emission, and emission sensitization of Si nanocrystals embedded in Si-rich oxide and Si-rich nitride. Based on the results of our study, we identify Si nanocrystal emission from Si-rich nitride and Er doping of Si-rich oxide as materials systems that satisfy the requirements of CMOS compatible processing and high emission efficiency for integration with Si-based electronics. We also present PbS quantum dot emission sensitization through Si nanocrystals in Si-rich nitride, an alternative approach to achieving efficient infrared emission on a Si platform. The improved electrical properties and high refractive index of Si-rich nitride also allows for the fabrication of electroluminescent devices with small footprints and active, complex photonic crystal devices for multiwavelength applications.

Light Emission from Silicon-based Nano-materials

This paper presents an overview of the research activities aimed at engineering novel, nanostructured-based materials solutions for CMOS-compatible electrically driven light sources. In particular, the state of the art of the optical and electrical properties of Si-nc nucleated within Si-rich nitride (SRN) matrices, and their large potential for energy sensitized, efficient 1.55mum electroluminescence under low injection fields are discussed

Light emitting silicon nanostructures

In this paper the main results on the energy sensitization and optical properties of light-emitting silicon based nanostructures for microphotonics applications are reviewed. The energy sensitization of erbium ions from silicon nanocrystals embedded in silicon-rich oxide (SRO) and silicon-rich nitride matrices (SRN) are discussed. For both the systems the efficient energy transfer to erbium ions is demonstrated. In addition, it is shown that SRN is a suitable material for the fabrication of optically active complex photonic crystal structures