We are aiming at creating sources and detectors of light of energy ranging from the THz domain to the deep UV. For this purpose, we benefit from the large variety of materials that are grown within the group. The control of the geometry of the nanostructure allows us to realize devices compatitble with conventionnal lighting applications down to systems which are sensitive to the single photon level. HEre are a few exmaple of the devices and application we are working on :
Thanks to their large conduction band offset (up to 1.75 eV for GaN/AlN), III-nitride nanostructures offer great prospects for ultrafast intersubband (ISB) devices operating at room temperature in the near-IR spectral range. NPSC has made a significant research effort on the development of a nitride ISB technology operating at 1.3 and 1.55 μm wavelength : interesting results were the development of the first ISB electro-optical modulators and quantum cascade detectors based on III-nitrides, as well as the record shortest ISB photoluminescence wavelength in semiconductors. Our present efforts focus on the measurement of electroluminescence in the far-infrared spectral range. This work will be extended to 1D structures (nanowires / nanorods), which should provide advantages in terms of both, control of the relaxation time thanks to the lateral confinement, and accessible material combinations and size of the active region thanks to the 3D elastic relaxation of misfit strain.
Our expertise in the growth of 1D nanowire semiconducting heterostructures, either by MBE or MOCVD, paves the way to the fabrication of light emitting diodes (LED) which are not affected by the structural defects which exist in present technolgy devices based on 2D layers. NPSC has been a major participant in the Carnot-Eclairage project, led by LETI-DOPT, and which leads to the creation of the start-up Aledia. We explored the growth of heterostructured nanowires by MBE and MOCVD and their optical characterization, and provided LETI with nanowire diode structures to be processed.
Our current efforts move now the the UV domain. We aim at developing solid-state light source emitting at wavelengths below 310nm in order to obtain a bactericidal effect. They would conveniently replace the conventional mercury vapor light tubes which are highly polluting. The team explores to different path to reach this goal : GaN/AlN quantum dots with carrier injection by field effect with the help of carbon nanotube or MBE grown nanowires made of AlxGa(1-x)N
The aim of these experiment are twofold : (i) we want to understand the behavior at the most fundamental level of a semiconducting light source or detector, in close relation to quantum optics and (ii) from a more practical point of view such device could be easily interfaced to integrated optics system and are paramount in quantum communication (single photon light source). We are currently investigating LEDs or detectors made of a single nanowire grown by MOCVD, microlasers made of a photonics bangap crystals or whisperring gallery mode with the aim or developping nonlinear light source (frequency doubling or parametric radiation), or trying to couple a single quantum dot embedded in a nanowire to dielectric or plasmonic nanoantennas
Most of the researches on III-N nanowires are oriented toward light emitting devices. In order to diversify the applications of these nano-objects to nanoelectronic domain, we investigate the electron transport through III-N double tunnel barriers in nanowires. Such a study is the first important step towards a variety of novel quantum devices relying on axial quantum confinement. This work is not only valuable for III-N nanowire applications but also for understanding quantum transport in nitride material which is mostly unexplored.
III-nitride semiconductors have launched the first optoelectronic revolution of the XXI century with the advent of solid-state blue lasers (Blue-ray) and LED lighting (mercury-free lamps, outdoor full-color screens, LED TV). On the other hand, the reduction of semiconductor dimensionality to the nanoscale has paved the way to the fabrication of optoelectronic devices whose color is not determined by the semiconductor band gap but by the geometrical design. Night-vision QWIP cameras or quantum cascade lasers are examples of devices exploiting quantum phenomena in low-dimensional nanostructures using classical compound semiconductors (arsenides, phosphides). The application of these principles to III-nitrides set the basis for a new technology to cover the infrared (IR) spectrum, from the fiber-optic telecom wavelengths (near IR) to the THz band (far IR), spectral domain that is relevant for non-invasive medical diagnosis, pollution monitoring and detection of a variety of pharmaceutical chemicals, explosives or bio-agents.
People : Edith Bellet-Amalric, Eirini Sarigiannidou, and Eva Monroy Fabien Guillot, Sylvain Leconte Overview and results : III-nitride semiconductors (GaN, AlN, InN) are currently the materials of choice for optoelectronic devices in the green to UV spectral region. A new prospect for... > suite