Manufacturing and characterization of III-V on silicon multijunction solar cells

Tandem GaInP/GaAs//Si(inactive) solar cells were manufactured by direct wafer bonding under vacuum. At this early stage, an inactive silicon substrate was used (i.e. n+ Si substrate instead of an active n-p Si junction). Bonded devices presented an Sshaped J-V curve with a kink close to Voc caused by a built-in potential barrier at the III-V//Si interface that reduces the fill factor and therefore the efficiency of the device by 7% compared to the stand-alone GaInP/GaAs tandem cells. Nevertheless, losses in Jsc and Voc caused by the bonding process, account for less than 10%. AlGaAs single junction cells, designed to be bonded on a silicon cell for low concentrator photovoltaics (LCPV), were also manufactured reaching an efficiency of 15.9% under one sun AM1.5G spectrum for a 2 cm² cell

Hybrid III-V on silicon lasers for photonic integrated circuits on silicon

This paper summarizes recent advances of integrated hybrid InP/SOI lasers and transmitters based on wafer bonding. At first the integration process of III-V materials on silicon is described. Then the paper reports on the results of single wavelength distributed Bragg reflector lasers with Bragg gratings etched on silicon waveguides. We then demonstrate that, thanks to the high-quality silicon bend waveguides, hybrid III-V/Si lasers with two integrated intra-cavity ring resonators can achieve a wide thermal tuning range, exceeding the C band, with a side mode suppression ratio higher than 40 dB. Moreover, a compact array waveguide grating on silicon is integrated with a hybrid III-V/Si gain section, creating a wavelength-selectable laser source with 5 wavelength channels spaced by 400 GHz. We further demonstrate an integrated transmitter with combined silicon modulators and tunable hybrid III-V/Si lasers. The integrated transmitter exhibits 9 nm wavelength tunability by heating an intra-cavity ring resonator, high extinction ratio from 6 to 10 dB, and excellent bit-error-rate performance at 10 Gb/s

Interface growth mechanism in Ion Beam Sputtering deposited Mo/Si multi-layers

International audienceDespite the technological importance of Metal/Si multilayer structure in Microelectronics, the interface reactions occurring during their preparation are not fully understood, yet. In this work, the interface intermixing in Mo/Si multilayer coatings has been studied with respect to their preparation conditions. Various samples prepared at room temperature with different Mo deposition rates (0.06-0.43 Å/s) and a constant Si one have been investigated by detailed TEM observations. Contrary to the Si-on-Mo interface where no evidence of chemical intermixing could be found, the Mo-on-Si interface presents a noticeable interface zone whose thickness was found to noticeably decrease (from 4.1 to 3.2 nm) when increasing the Mo deposition rate. Such intermixing phenomena correspond to diffusion mechanisms having coefficients ranging from 0.25 to 1.2.10-15 cm²/s at room temperature. By assuming a diffusion mechanism mainly driven by Mo-Si atomic exchanges to minimize the surface energy, the diffusion dependence with Mo deposition rate has been successfully simulated using a cellular automaton. A refined simulation including Mo cluster formation is also proposed to explain the scenario leading to the full crystallisation of Mo layers

New Nonlinear Electrical Modeling of High-Speed Electroabsorption Modulators for 40 Gb/s Optical Networks

International audienceA specific modeling method is investigated in order to predict the large-signal modulation behavior of integrated electroabsorption modulators (EAMs) for high-speed applications in optical networks. The equivalent dynamic model includes the main nonlinearity of the EAM and takes into account the electrical and optical characteristics of the optoelectronic device. The developed specific design process is a suitable and powerful tool for simulating over wide dc bias and frequency ranges, scattering parameters, small-signal modulation response, and large-signal eye-diagram performance. Moreover, 3-D electromagnetic simulations are associated with circuit simulations to carry out for the RF input line of the EAM. This simulation model can be easily integrated in a global optical communication system simulator to estimate the temporal behavior of the modulated output optical power and then digital performances

Modélisation hybride pour l'intégration de composants Electro-Optique à 100 Gbit/s

National audienc

First demonstration of dispersion limit improvement at 20 Gb/s with a dual electro-absorption modulated laser

International audienceWe successfully demonstrate experimentally and by simulation an error-free 39.7-km transmission at 20 Gb/s in standard dispersion fiber without any compensation fiber using Dual Electro-absorption Modulated Laser

Silicon bottom subcell optimization for wafer-bonded III-V on Si multijunction solar cells

International audienceCombining III-V and Si subcells by wafer bonding is an interesting approach for III-V on Si multijunction solar cells since it allows direct connection through a permanent, electrically conductive, transparent interface. However, it is not possible touse conventional Si homo-junctions solar cells, which usually are formed by diffusion processes on square or pseudo-square Sisubstrates with textured front surface. Some of the requirements on the bottom Si subcell for high efficient III-V on Siphotovoltaics by wafer bonding are: (i) high bulk minority carrier lifetime, (ii) low recombination at III-V/Si interface thanks toadequate emitter doping and/or III-V/Si interface passivation, (iii) low defective and smooth front Si surface, which often requires the use of chemo-mechanical polishing (CMP) and hence also impacts the emitter doping. In this paper, we compare diffusion, beamline ion implantation and plasma immersion ion implantation doping processes with different thermal activationtreatments for the optimization of the Si bottom subcell. Resulting one-sun power conversion efficiency of III-V on Si two-terminal triple-junction (3J) devices increased from 25.2% for non-current matched GaInP/AlGaAs/Si reported in our previous work to >26% for GaInP/GaAs/Si (28.6% under 30 suns), highlighting that the design of bottom Si subcell is extremely important for current matching in two-terminal tandem cell design

First space concentrator prototype using III-V/Si cells

International audienc