Jean-Baptiste Rodriguez

Silicon-Based Photonic Integration Beyond the Telecommunication Wavelength Range

In this paper we discuss silicon-based photonic integrated circuit technology for applications beyond the telecommunication wavelength range. Silicon-on-insulator and germanium-on-silicon passive waveguide circuits are described, as well as the integration of III-V semiconductors, IV-VI colloidal nanoparticles and GeSn alloys on these circuits for increasing the functionality. The strong nonlinearity of silicon combined with the low nonlinear absorption in the mid-infrared is exploited to generate picosecond pulse based supercontinuum sources, optical parametric oscillators and wavelength translators connecting the telecommunication wavelength range and the mid-infrared.

Silicon-on-insulator spectrometers with integrated GaInAsSb photodiodes for wide-band spectroscopy from 1510 to 2300 nm

We present a silicon-on-insulator (SOI) based spectrometer platform for a wide operational wavelength range. Both planar concave grating (PCG, also known as echelle grating) and arrayed waveguide grating (AWG) spectrometer designs are explored for operation in the short-wave infrared. In addition, a total of four planar concave gratings are designed to cover parts of the wavelength range from 1510 to 2300 nm. These passive wavelength demultiplexers are combined with GaInAsSb photodiodes. These photodiodes are heterogeneously integrated on SOI with benzocyclobutene (DVS-BCB) as an adhesive bonding layer. The uniformity of the photodiode characteristics and high processing yield, indicate a robust fabrication process. We demonstrate good performance of the miniature spectrometers over all operational wavelengths which paves the way to on-chip absorption spectroscopy in this wavelength range.

Continuous-wave operation above room temperature of GaSb-based laser diodes grown on Si

We have investigated specifically designed GaSb-based laser diodes epitaxially grown on a Si substrate. We demonstrate continuous-wave operation of these laser diodes emitting near 2 μm up to 35 °C with several mW/facet output powers, limited by our experimental setup. Our results open the way to direct monolithic III-V/Si integration.

GaSb-Based Laser, Monolithically Grown on Silicon Substrate, Emitting at 1.55

We have investigated the potential of GaSb-based lasers for emission at 1.55 μm and monolithic integration on silicon. We designed an active region based on strained Ga_0.8In_0.2Sb quantum-wells aiming a good carrier confinement. To validate this design, the active region was first used in edge-emitting lasers grown on GaSb substrates. Continuous-wave operation at 1.56 μm has been achieved up to 45°C. The same laser structure grown on Si substrate showed room-temperature operation in pulsed regime at 1.55 μm with a threshold current density of 5 kA/cm².

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In this paper, we studied wet chemical etching fabrication of the InAs/GaSb superlattice mesa photodiode for the mid-infrared region. The details of the wet chemical etchants used for the device process are presented. The etching solution is based on orthophosphoric acid (H3PO4), citric acid (C6H8O7) and H2O2, followed by chemical polishing with the sodium hypochlorite (NaClO) solution and protection with photoresist polymerized. The photodiode performance is evaluated by current?voltage measurements. The zero-bias resistance area product R0A above 4 ? 105 ? cm2 at 77 K is reported. The device did not show dark current degradation at 77 K after exposition during 3 weeks to the ambient air.

m at Room Temperature

In this communication we report on electrical properties of nonintentionally doped (nid) type II InAs/GaSb superlattice grown by molecular beam epitaxy. We present a simple technological process which, thanks to the suppression of substrate, allows direct Hall measurement on superlattice structures grown on conductive GaSb substrate. Two samples were used to characterize the transport: one grown on a semi-insulating GaAs substrate and another grown on n-GaSb substrate where a etch stop layer was inserted to remove the conductive substrate. Mobilities and carrier concentrations have been measured as a function of temperature (77–300 K), and compared with capacitance-voltage characteristic at 80 K of a photodiode comprising a similar nid superlattice.

Wet etching and chemical polishing of InAs/GaSb superlattice photodiodes

We report on a Sb-based type-I laser grown on GaAs substrate, emitting continuous wave at room temperature around 2.2 μm. The device was grown using solid-source molecular beam epitaxy and comprised two GaInAsSb quantum wells embedded in AlGaAsSb barriers. Despite the large lattice mismatch, a good crystalline quality was obtained, and processed devices operated continuous wave up to 50 °C with threshold current densities in the range of 1.5–2.2 kA/cm2. An optical output power of 3.7 mW was obtained at 20 °C.

Unambiguous determination of carrier concentration and mobility for InAs/GaSb superlattice photodiode optimization

We report on a type-II InAs/GaSb strained layer superlattice (SLS) photodetector (λ ~4.3 µm at 77 K) with nBn design grown on a GaAs substrate using interfacial misfit dislocation arrays to minimize threading dislocations in the active region. At 77 K and 0.1 V of the applied bias, the dark current density was equal to 6 × 10−4 A cm−2 and the maximum specific detectivity D* was estimated to 1.2 × 1011 Jones (at 0 V). At 293 K, the zero-bias D* was found to be ~109 Jones which is comparable to the nBn InAs/GaSb SLS detector grown on the GaSb substrate.

GaSb-based, 2.2 μm type-I laser fabricated on GaAs substrate operating continuous wave at room temperature

We report on structural, electrical, and optical characterizations of midwave infrared InAs/GaSb superlattice (SL) p-i-n photodiodes. High-quality SL samples, with 1 μm thick active region (220 SL periods), exhibited a cut-off wavelength of 4.9 μm at 80 K. Using a capacitance-voltage measurement technique performed on mesa diode, the residual background concentration in the nonintentionally doped region was determined to be 3×1015 cm−3 at 80 K. Extracted from current-voltage characteristics, R0A products above 4×105 Ω cm2 at 80 K were measured, and the quantitative analysis of the J-V curves showed that the dark current density of SL photodiode is dominated by generation-recombination processes. Front-side illuminated photodiodes produced responsivity at 80 K equal to 360 mA/W at 4.5 μm.

Mid-infrared InAs/GaSb strained layer superlattice detectors with nBn design grown on a GaAs substrate

The unique properties of the noncommon-atom InAs/GaSb short-period-superlattices (SPSL) strongly depend on the interface structure. These interfaces are characterized using transmission electron microscopy (TEM). The compositional sharpness is obtained from the comparison of the experimental contrast in g002 two-beam dark-field TEM images with simulated intensity profiles, which are calculated assuming that the element distribution profiles are described by sigmoidal functions. The interfacial intermixing, defined by the chemical width, is obtained for SPSL with different periods and layer thicknesses, even in the extreme case of nominally less than 3 ML thick InAs layers. Nominal 1 ML InSb layers intentionally inserted are also identified.The unique properties of the noncommon-atom InAs/GaSb short-period-superlattices (SPSL) strongly depend on the interface structure. These interfaces are characterized using transmission electron microscopy (TEM). The compositional sharpness is obtained from the comparison of the experimental contrast in g002 two-beam dark-field TEM images with simulated intensity profiles, which are calculated assuming that the element distribution profiles are described by sigmoidal functions. The interfacial intermixing, defined by the chemical width, is obtained for SPSL with different periods and layer thicknesses, even in the extreme case of nominally less than 3 ML thick InAs layers. Nominal 1 ML InSb layers intentionally inserted are also identified.