We present a study of the dynamic properties of electrons tunneling from an InGaAs quantum well to self assembled InAs quantum dots. The experiments were conducted on three highly asymmetric quantum dot infrared photodetectors, where the quantum well and quantum dots were separated by a composite GaAs/AlGaAs/GaAs barrier, which varied from 3.5 nm to 7.0 nm. We performed interband (photoluminescence) and intraband (photocurrent) measurements to characterize the spectral properties of the well and the dots. The photoluminescence measurements revealed that the two nanostructures are decoupled when the device is at zero bias. By intraband pump-probe experiments and photocurrent saturation experiments, we were able to extrapolate a refilling time τ from the well to the dots, which varied from a few μs for the thinnest barrier and hundreds of μs for the thickest one. The extracted values are in good agreement with characteristic tunneling times computed by using a model based on the theoretically predicted transmission coefficient of the electrons through the composite barrier.

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We present a study of the performance enhancement of a quantum dot infrared photodetector (QDIP), by means of complementary split-ring resonator (CSRR) nano-antennae. The QDIP is based on an asymmetric heterostructure containing a single layer of self-assembled InAs/GaAs quantum dots (QDs). The proximity of the QD plane to the top contact layer is exploited for the coupling with the near-field of the CSRR modes. The co-existence of the CSRR LC mode, at λLC = 7.4 μm, and of non-localized Bragg-like modes, is observed for the two-dimensional array of nano-antennae implemented on the QDIP. At λLC and a temperature T = 10 K, the antenna coupled device is characterized by a responsivity of 44 μA/W and a specific detectivity D* = 1.5 × 108Jones. For the highly localized LC mode, enhancements of a factor 1.7 in responsivity and 2.1 in specific detectivity are observed. Within the sub-wavelength LC mode effective surface, normalizing the overall response to the active surface of the detector, a responsivity enhancement of ∼19 is estimated, showing the potentiality of this approach for the realization of high-performance QDIPs working at normal incidence.

The tremendous demand for low-cost, low-consumption and high-capacity optical transmitters in data centers challenges the current InP-photonics platform. The use of silicon (Si) photonics platform to fabricate photonic integrated circuits (PICs) is a promising approach for low-cost large-scale fabrication considering the CMOS-technology maturity and scalability. However, Si itself cannot provide an efficient emitting light source due to its indirect bandgap. Therefore, the integration of III-V semiconductors on Si wafers allows us to benefit from the III-V emitting properties combined with benefits offered by the Si photonics platform. Direct epitaxy of InP-based materials on 300 mm Si wafers is the most promising approach to reduce the costs. However, the differences between InP and Si in terms of lattice mismatch, thermal coefficients and polarity inducing defects are challenging issues to overcome. III-V/Si hetero-integration platform by wafer-bonding is the most mature integration scheme. However, no additional epitaxial regrowth steps are implemented after the bonding step. Considering the much larger epitaxial toolkit available in the conventional monolithic InP platform, where several epitaxial steps are often implemented, this represents a significant limitation. In this paper, we review an advanced integration scheme of AlGaInAs-based laser sources on Si wafers by bonding a thin InP seed on which further regrowth steps are implemented. A 3 µm-thick AlGaInAs-based MutiQuantum Wells (MQW) laser structure was grown onto on InP-SiO2/Si (InPoSi) wafer and compared to the same structure grown on InP wafer as a reference. The 400 ppm thermal strain on the structure grown on InPoSi, induced by the difference of coefficient of thermal expansion between InP and Si, was assessed at growth temperature. We also showed that this structure demonstrates laser performance similar to the ones obtained for the same structure grown on InP. Therefore, no material degradation was observed in spite of the thermal strain. Then, we developed the Selective Area Growth (SAG) technique to grow multi-wavelength laser sources from a single growth step on InPoSi. A 155 nm-wide spectral range from 1515 nm to 1670 nm was achieved. Furthermore, an AlGaInAs MQW-based laser source was successfully grown on InP-SOI wafers and efficiently coupled to Si-photonic DBR cavities. Altogether, the regrowth on InP-SOI wafers holds great promises to combine the best from the III-V monolithic platform combined with the possibilities offered by the Si photonics circuitry via efficient light-coupling.