Jinsong Xia

Room-temperature electroluminescence from Si microdisks with Ge quantum dots

A current-injected silicon-based light-emitting device was fabricated on silicon-on-insulator (SOI) by embedding Ge self-assembled quantum dots into a silicon microdisk resonator with p-i-n junction for current-injection. Room-temperature resonant electroluminescence (EL) from Ge self-assembled quantum dots in the microdisk was successfully observed under current injection, and observed EL peaks corresponding to the whispering gallery modes (WGMs) supported by the microdisk resonator were well identified by means of numerical simulations.

Observation of whispering-gallery modes in Si microdisks at room temperature

Whispering-gallery modes are observed at room temperature in silicon microdisk resonators fabricated on silicon-on-insulator substrates. Sharp luminescent peaks originating from the crystalline silicon film, corresponding to the whispering-gallery modes, are observed to change in microdisks with different diameters. Over 30 times enhancement of the photoluminescence from bulk silicon is observed due to the microdisk.

Generation and Wavelength Control of Resonant Luminescence from Silicon Photonic Crystal Microcavities with Ge Dots

Ge self-assembled quantum dots were embedded into two-dimensional photonic crystal microcavities fabricated on silicon-on-insulator substrates by gas-source molecular beam epitaxy (GS-MBE), electron beam lithography, and reactive ion etching (RIE). Light-emission characteristics of Ge quantum dots in the microcavities were characterized by room-temperature microphotoluminescence. Multiple sharp resonant luminescent peaks with quality factors of up to 600, corresponding to the resonant modes supported by the cavity, were observed in the emission range of Ge quantum dots. Control of the wavelengths of the photoluminescence peaks over a wide range from 1.3 to 1.6 µm was demonstrated by adjusting the lattice constant of the photonic crystals. The results show that embedding Ge dots into optical microcavities is a possible candidate for silicon-based light emitting devices.

(Invited) Electroluminescence from Micro-Cavities of Photonic Crystals, Micro-Disks and Rings Including Ge Dots Formed on SOI Substrates

We fabricated Si micro-cavities with Ge dots and successfully observed electroluminescence at room temperature. In the case of micro-disks, we observed both modes of whispering gallery modes and Fabry-Perot modes in photoluminescence, but the latter was found to be well eliminated from micro-rings. For photonic crystals, we observed systematic dependence of PL peaks on the structure parameters such as the diameter and period of air holes and crystal pattern. More than one thousand of Q-factor was observed in these photonic crystals. Well resolved electroluminescence peaks were observed both for micro-disks and photonic crystals at room temperature. However, the line width was found to be much broader than that of PL samples, probably due to the additional metal electrodes, oxide films and doping regions which are not included in PL samples. Moreover, the peak shift to higher energies coming from thermal treatment for diode fabrication was observed.

Current-injected light emitting device based on Si microdisk with Ge dots

To fabricate a current-injected silicon-based light emitting device, Ge quantum dots were embedded into a microdisk resonator with P-I-N juction for current-injection. Room-temperature electroluminescence was observed from the dots in the microdisk.

Enhanced Light Emission from Ge Quantum Dots in Microdisks

Ge self-assembled quantum dots embedded into microdisk resonators are fabricated by a combination of gas-source molecular beam epitaxy, electron beam lithography and reactive ion etching. Scanning electron microscopy and microphotoluminescence are used to characterize the quantum dots. Room temperature mu-PL measurements show that the light emission from Ge dots is significantly enhanced by the microdisks.

Enhanced Light-emission from Crystalline Silicon in Microdisk Resonators

Microdisks were fabricated on silicon-on-insulator. Sharp resonant luminescent peaks, corresponding to the whispering-gallery modes, were observed in the disks. Integral photoluminescence intensity from crystalline silicon was significantly enhanced due to the microdisks.

Controlled Photoluminescence from Ge Quantum Dots in Photonic Crystal Microcavities

In this paper, we use photonic crystal microcavity to enhance and control the photoluminescence from Ge self-assembled quantum dots. The microcavities are formed by introducing defects into two dimensional PhC slab on silicon-on-insulator (SOI). Strong resonance luminescence is observed at room temperature and the wavelengths of the luminescence peaks are adjusted by changing the PhC parameters

Two-dimensional Photonic Crystal Microcavity with Germanium Self-assembled Quantum Dots

We fabricated two-dimensional photonic crystals on silicon-on-insulator substrate. Ge/Si self-assembled quantum dots were embedded in the PhC cavity as light emitters. The photoluminescence spectra of H1 cavity at room temperature showed strong optical resonance in the cavity. Significant enhancement of the luminescence was achieved and a main peak at 1.43 mum was seen to dominate the spectrum. Reasonable shift of the resonant peak wavelength was observed by changing the PhC parameters. The results prove that combination between photonic crystal and Ge quantum dots is a reasonable way to realize Si-based light source.