Etude par microscopie electronique en transmission de semiconducteurs II-VI epitaxies par jets moleculaires

SIGLECNRS T 64605 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Toward Eco-Design of a 5G mmWave Transmitarray Antenna Based on Life Cycle Assessment

International audience5G is seen as one technology enabler to support the expected exponential internet data-traffic growth while digitization environmental impacts are growing. Base stations are estimated to represent the main contributor to mobile internet access network carbon footprint. In this work, life cycle assessment (LCA) of a 26 GHz transmitarray antenna is described taking into consideration the geographical location of the antenna use and providing eco-design leads to researchers, designers, LCA practitioners and industrials. Results show that energy consumption during operation is the main source of impact (between 72% and 94% for most impacts), while the material depletion is largely generated by the manufacturing process (99.3%). As a result, the eco-design must focus on product energy efficiency as well as material depletion during manufacturing. The impact of usage is highly dependent on the location due to the diverse electricity mix of countries. An ecodesign solution using phase-change material (PCM) technology switches is compared to a conventional approach using GaAs pin diodes. These results pave the way for reducing the impacts of transmitarray antennas and are a first step towards more sustainable solutions for millimeter wave (mmWave) networks

Design and optimization of electrically injected InP-based microdisk lasers integrated on and coupled to a SOI waveguide circuit

We have performed a numerical study involving the design and optimization of InP-based microdisk lasers integrated on and coupled to a nanophotonic silicon-on-insulator (SOI) waveguide circuit, fabricated through bonding technology. The theoretical model was tested by fitting it to the lasing characteristics obtained for fabricated devices, which we presented. previously. A good fit was obtained using parameter values that are consistent with numerical simulation. To obtain optimized laser performance, the composition of the InP-based epitaxial layer structure was optimized to minimize internal optical loss for a structure compatible with efficient current injection. Specific attention was paid to a tunnel-junction based approach. Bending loss was quantified to estimate the minimum microdisk diameter. The coupling between the InP microdisk and Si waveguide was calculated as function of the bonding layer thickness, waveguide offset and waveguide width. To study the lateral injection efficiency, an equivalent electrical network was solved and the voltage-current characteristic was calculated. Based on these results, the dominant device parameters were identified, including microdisk thickness and radius, coupling loss and tunnel-junction p-type doping. These parameters were optimized to obtain maximum wall-plug efficiency, for output powers in the range 1-100 mu W. The results of this optimization illustrate the potential for substantial improvement in laser performance

A compact SOI-integrated multiwavelength laser source based on cascaded InP mircrodisks

We report on the performance of a compact multiwavelength laser (MWL) source heterogeneously integrated with and coupled to a silicon-on-insulator (SOI) waveguide circuit. The MWL consists of four InP-based microdisk lasers, coupled to a common SOI wire waveguide. The microdisk lasers operate in continuous-wave regime at room temperature, with a threshold current around 0.9 mA and a waveguide-coupled slope efficiency of up to 8 mu W/mA, for a microdisk diameter of 7.5 mu m. The output spectrum contains four laser peaks uniformly distributed within the free-spectral range of a single microdisk. While thermal crosstalk is negligible, laser peak output powers vary up to 8 dB for equal microdisk drive currents, as a result of loss due to coupling with higher order modes supported by the 1-mu m-thick microdisks. This nonuniformity could be eliminated by reducing the microdisk thickness

SiC Power Devices on QUASIC and SiCOI Smart-Cut^® Substrates: First Demonstrations

Wafer bonding technologies have been recognized to provide new substrates structures suitable for the development of Si power devices. Among the multiple examples that could be listed, the possibility to generate PN junctions without thick epitaxial growth and lateral devices onto dielectrically isolated substrates such as SOI (Silicon On Insulator) are significant examples of the interest proposed by wafer bonding. Thin film substrates obtained with the Smart-Cut® technology such as SiCOI (SiC On Insulator) substrates for lateral devices and QUASIC substrates for vertical power devices have already been demonstrated. In this article, we review the recent developments in the field of SiC power devices using these two kinds of SiC Smart-Cut substrates. Lateral and vertical Schottky diodes have been processed onto SiCOI and QUASIC substrates as a demonstration of feasibility. Simulations, results and prospects are presented in this article

Low-footprint optical interconnect on an SOI chip through heterogeneous integration of InP-based microdisk lasers and microdetectors

We present a proof-of-principle demonstration of a low-footprint optical interconnect on a silicon-on-insulator (SOI) chip. The optical link consists of a heterogeneously integrated, InP-based microdisk laser (MDL) and microdetector, coupled to a common SOI wire waveguide. Applying an electrical current to the MDL resulted in a detector current up to 1 mu A