Effect of well confinement on photoluminescence features from silicon nanoparticles embedded in an SiC/SiN_xmultilayered structure

Abstract

Light emission from a quantum well-dot structure comprising amorphous Si nanoparticles (∼1.4 nm) embedded in SiC/SiN(x) multilayers (a few tens nm thick for individual sublayers) was investigated. Strong blue-green photoluminescence was measured at room temperature on the as-deposited samples and the spectral profile shows some markedly modulated features. It displays flattened profiles of roughly equal intensity when silicon particles in both nitride and carbide sublayers can be effectively excited, whereas when the nitride sublayer is less effectively activated at longer excitation wavelength the photoluminescence is pinned (here at 500 nm), showing a rather narrow, slowly decreasing profile. The phenomenon of narrowed emission is also observed in the Si-in-SiC multilayer consisting of particles of varying size distributions. Resonance energy transfer processes among particles modified by carrier confinement may provide a reasonable explanation.

Evolution of photoluminescence properties of Si1−xGex nanocrystals synthesized by laser-induced pyrolysis

“…It is the quantum confinement effect, which plays an essential role in the light emission of silicon-based NCs, allowing one to obtain flexible control over the energy of optical radiative transitions and their efficiency. Various techniques such as laser pyrolysis, 1,2 magnetron sputtering, 3,4 silicon ion implantation, 5,6 and plasma-enhanced chemical vapor deposition 7,8 have been employed to obtain three dimensionally confined Si NCs, among which laser pyrolysis is preponderant in producing matrix-free Si NCs with controllable size.…”

Multi-band silicon quantum dots embedded in an amorphous matrix of silicon carbide

“…These PL sub-bands in 7(a) can be divided into two ranges: 2.3-3.0 and 3.0-3.5 eV. The sub-bands in the range of 2.3-3.0 eV are attributed to the QCE of c-Si QDs with different sizes [36], while the higher energy PL sub-bands within 3.0-3.5 eV might be attributed to ultra-small amorphous Si QDs (∼1 nm). They are formed in the infancy of c-Si QDs, as revealed by GIXRD patterns and Raman spectra.…”

Femtosecond laser crystallization of amorphous Ge

“…Crystallization of amorphous materials can be achieved with different techniques such as furnace and rapid thermal annealing, 1 ion beam treatment, 2 pulsed and cw laser annealing. [3][4][5] Laser induced crystallization of amorphous structures reduce thermal budget and provide crystallization of predetermined patterns down to sizes only limited by diffraction of light allowing space selective writing of crystalline structures in amorphous matrices.…”

“…Many types of lasers have been used in the past to crystallize amorphous semiconductors. 3,4 Recent advances in ultrafast lasers in the femtosecond time regime allows us to exploit solid and liquid state crystallization of amorphous semiconductors in the ultrafast regime. Unlike nanosecond or picosecond time regimes, energy deposition in the femtosecond time regime which is faster than electron-phonon interaction times can lead to excitation of electron densities beyond those required for lattice stability.…”