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International audience; This paper reports on pin photodiode frequency response optimization based on InxGa1-xAs1-yNy quaternary lattice matched to GaAs. Two transparent layers are placed on p-side and n-side in order to manage the photodiode frequency response limitations. The lattice matching condition is calculated in order to obtain stable structure. The physical and optical parameters calculations are performed at room temperature showing the impact of nitrogen on the absorption coefficient. A stable structure, having 2 % of nitrogen and 6% of indium, allows to achieve a cutoff frequency of about 116 GHz and a capacitance of 5.21fF while the quantum efficiency is 41.59% for a depletion region thickness of about 0.55 µm. However, in case of depletion region thickness of about 0.625 µm, the cutoff frequency degrades to 98 GHz while the capacitance diminishes to 4.58fF and the quantum efficiency increases to 51.56%. In addition, a comparative study with literature results has been carried out in order to show the advantages of the proposed photodiode. This comparison affirms that the proposed photodiode based on InGaAsN lattice matched to GaAs exhibits high-speed photo-detection. This work allowed us to obtain a p-i-n photodiode with stable structure suitable for photo-detection at 1.15 µm.

International audience; We present the experimental determination of the complex permittivity of vertically aligned single wall carbon nanotubes (SWCNTs) films grown on quartz substrates in the microwave regime from 10 MHz up to 67 GHz, with the electrical field perpendicular to the main axis of the carbon nanotubes (CNTs), based on coplanar waveguide transmission line approach together with the measurement of the microwave impedance of top metalized vertically-aligned SWCNTs grown on conductive silicon substrates up to 26 GHz. From coplanar waveguide measurements, we obtain a real part of the permittivity almost equal to unity, which is interpreted in terms of low carbon atom density (3 x 10(19) at/cm(3)) associated with a very low imaginary part of permittivity (< 10(-3)) in the frequency range considered due to a very small perpendicular conductivity. The microwave impedance of a vertically aligned CNTs bundle equivalent to a low resistance reveals a good conductivity (3 S/cm) parallel to the CNTs axis. From these two kinds of data, we experimentally demonstrate the tensor nature of the vertically grown CNTs bundles.

In this paper, the frequency response calculation and optimization of PIN photodiodes based on GaN/InGaN, suitable for photodetection at the wavelength of 633 nm, are presented. The calculations of the impulse as well as the frequency response are performed using the impulse method. The frequency response optimization is a result of optimizing the transport of photo-generated carriers in the absorbent layer of the photodiode, using a mixed depletion region rather than a single absorbing depletion region. Cut-off frequencies of about 82 GHz and 48 GHz have been obtained in the case of transparent layer thickness of 500 nm and 1000 nm, respectively. The aforementioned results represent a very good improvement.

This Letter reports on new experimental high dynamic range sub-sampling performances obtained from nanoscale microwave photoconductive switches operating under a 0.8 µm wavelength pulsed illumination. Experimental results have been performed on different samples benefiting of a low temperature grown Gallium Arsenide absorbing layer on GaAs substrate, coplanar microwave electrode profile optimisation, and the use of an ultra-low noise jitter optical source delivering optical pulses of 1 to10 ps pulse width at a 2 GHz repetition frequency at 0.8 µm optical wavelength. Thanks to carrier lifetime tunability achievement from 1 to 20 ps, in association with a carrier mobility of 3900 cm²/V.s, experimental demonstrations of 54 and 45 dB signal-to-noise ratio microwave signal sampling for signals at 5,76 and 20 GHz frequency bandwidth respectively confirms submicron devices functionality as a new class of single channel photonic analogue to digital converters.

In the manufacturing processes of high-power laser diode modules, the module packaging technologies play an important role; decide the efficiency of the electro-optical conversation, the beam quality and the lifetime. This paper presents the packaging of high-power laser diode modules from single chip, evaluating the electro-optical characteristics and the beam quality of the modules. The obtained results show that the packaged module has an output optical power of 5 W at current 5.9 A; the Operation Voltage is 1.7 V; the Threshold Current is 1,0 A; the Divergence Angle Mean is 36.8 degree and the Asymmetry is 1.04. These parameters are almost the same that of some on-stock modules. Thus, the application of the packaged module in social – economics is possible. Keywords: Laser diode, fiber – coupled, die bond technology; wire bond technology; electro-optical conversation efficiency, PVI characteristics, beam quality, Divergence Angle, Asymmetry.

The main purpose of this paper is to show the effect of charge accumulation and screening of the electric field on the Schottky Metal-semiconductor-Metal detector response and efficiency, which result of non-uniform distribution carriers along the absorption depth, and along the line between electrodes. The MSM (PD) with an active surface of 3×3 µm2 and electrode spacing of 0.2, 0.3, 0.5 and 1 µm has been integrated in the central strip of coplanar lines for microwave switching application. Several ways of improving the high-speed response of the MSM-PD are analyzed and discussed.

International audience; In this work, we report a comparative investigation of InxGa1-xN (SL) and InxGa1-xN/GaN (MQW) structures with an indium content equivalent to x=10%. Both structures are grown on (0001) sapphire substrates using MOCVD and MBE growth techniques. Optical properties are evaluated for samples using PL characteristics. Critical differences between the resulting epitaxy are observed. Microstructures have been assessed in terms of crystalline quality, density of dislocations and surface morphology. We have focused our study towards the fabrication of vertical PIN photodiodes. The technological process has been optimized as a function of the material structure. From the optical and electrical characteristics, this study demonstrates the benefit of InGaN/GaN MQW grown by MOCVD in comparison with MBE for high speed optoelectronic applications.

Photogenerated carriers in a photodiode drift in the junction before joining the circuit. We must use a quite thin depletion region so that their transit time does not penalize the microwave response of the devices. However, when the depletion region decreases the component capacity increases, which highly limits the microwave response of this latter. Replace the completely absorbent depletion region by a mixed depletion region increases the pure transit cut-off frequency for the same thickness of the depletion region. We use this property in what follows to optimize the performance of PIN photodiode based on InP/InGaAs, adapted for the photodetection at the wavelength of 1.55 μm. The obtained results show that the maximum area of photodiodes with mixed depletion regions with thin absorbent exceeds by 64% that of the photodiodes with completely absorbent depletion regions for the same bandwidth. Their maximum absorption volume exceeds by 8% that of the photodiodes with completely absorbent depletion regions for the same bandwidth. Both types of components are also compared on the abacuses when the thickness of the absorbent and the surface are imposed.