Tunable Luminescence from a Silicon‐Rich Oxide Microresonator

Abstract

Wavelength tunability is a key aspect for light-emitting materials, and is one of the critical properties driving research on semiconductor quantum dots [1] and organic microcavity devices.[2] Narrow and well-defined emission spectra are important with respect to the development of optical displays, optical amplifiers, light-emitting diodes, and ªtunableº quantum dot lasers. [3] Silicon-based light emitters, in particular, represent a key technology that may challenge the bottlenecks currently facing the microelectronics industry; [4] however, widely tunable and spectrally narrow ªquantum-dot-likeº emission has remained problematic. Here, we demonstrate that siliconrich oxide can be processed at temperatures compatible with silicon microelectronics, while at the same time, the emission wavelength can be tuned throughout the visible spectrum and extended to the fiber-optic transparency windows in the near infrared. This approach covers most of the 0.4 to 1.6 lm wavelength range needed for silicon-based photonics, [4] produces the widest spectral tunability achieved for any single material, and presents an attractive silicon-based alternative to quantum dot or microcavity organic light-emitting materials for photonic applications. Silicon nanocrystal composites are currently the focus of the intense international research efforts that may foreshadow the ªoptical age of siliconº.[5] These efforts are driven by potential photonic applications of silicon-based materials in light-emitting diodes (see, for example, the work of Valenta and co-workers [6] ), nanocrystal lasers, [7,8] and erbium-doped waveguide amplifiers (see, for example, the work of Franzò and co-workers [9] ). Silicon nanocrystal composites represent one of the best hopes for photon creation and transmission in next-generation optical interconnects.[4] Silicon nanocrystals in SiO 2 have a broad luminescence band centered in the near infrared, with a photoluminescence quantum efficiency several orders of magnitude higher than that of bulk silicon.[10]When placed within a distributed Bragg reflector (DBR) structure, the emission is intensified and spectrally narrowed, [11,12] although it is still within the 700±900 nm range characteristic of the natural emission. Nevertheless, this type of fine wavelength control is of recognized importance with respect to luminescent devices. [8] A simpler microcavity consisting of a bottom dielectric stack and a top silver mirror was recently used for a silicon nanocomposite, [13] but wavelength tunability was not demonstrated and the optical modes were broad. One of the main drawbacks with respect to device integration is the high processing temperature (generally at least 1000 C) required to form luminescent silicon nanoparticles via phase separation of a material with excess atomic silicon. Such high temperatures are incompatible with CMOS (complementary metal oxide semiconductor) technology [14] and, from the point of view of DBRs, make the fabrication of devices based on these materials more difficult, ...

Luminescence of Nd-enriched silicon nanoparticle glasses

“…Indeed, we have demonstrated the existence of amorphous Si-rich clusters in SiO processed at 500°C [11], and that the presence of these clusters is responsible for the broad PL band in the visible part of the spectrum [12]. Of particular importance is the fact that effective Nd emission can be obtained at temperatures as low as 400°C, which makes trial device fabrication considerably easier.…”

Silicon Filaments in Silicon Oxide for Next‐Generation Photovoltaics

“…In thin-film silicon solar cells, such filamentous SiO x helps reduce absorption losses in the doped layers, and its tunable refractive index allows for advanced light management by engineering reflection or anti-reflection effects within the cell. When undoped, the silicon filaments show similar quantum confinement effects as spherical silicon particles in silicon oxide, [2][3][4][5] but their elongated forms and the low temperature deposition processes at 200 °C could facilitate device fabrication in all-silicon quantum "dot" photovoltaics [6,7] and other optoelectronic applications [8][9][10] (e.g. by allowing direct fabrication on conductive substrates).…”

Tuning visible emission by choosing excitation wavelength in Mg-doped ZnO/silica composites

“…Wavelength tunability is a key aspect for light-emitting materials [1], and is one of the critical properties driving research on semiconductor quantum dots [2,3]. As a direct band semiconductor with wide band-gap (∼3.3 eV at room temperature), wurtzite zinc oxide has attracted much attention as a luminescent material for both fundamental research and applications [4,5].…”