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The nanoscale intrinsic electrical properties of in-plane InAs nanowires grown by selective area epitaxy are investigated using a process-free method involving a multi-probe scanning tunneling microscope. The resistance of oxide-free InAs nanowires grown on an InP(111)B substrate and the resistance of InAs/GaSb core–shell nanowires grown on an InP(001) substrate are measured using a collinear four-point probe arrangement in ultrahigh vacuum. They are compared with the resistance of two-dimensional electron gas reference samples measured using the same method and with the Van der Pauw geometry for validation. A significant improvement of the conductance is achieved when the InAs nanowires are fully embedded in GaSb, exhibiting an intrinsic sheet conductance close to the one of the quantum well counterpart. [ABSTRACT FROM AUTHOR]

In-plane InGaAs/Ga(As)Sb heterojunction tunnel diodes are fabricated by selective area molecular beam epitaxy with two different architectures: either radial InGaAs core/Ga(As)Sb shell nanowires or axial InGaAs/GaSb heterojunctions. In the former case, we unveil the impact of strain relaxation and alloy composition fluctuations at the nanoscale on the tunneling properties of the diodes, whereas in the latter case we demonstrate that template assisted molecular beam epitaxy can be used to achieve a very precise control of tunnel diodes dimensions at the nanoscale with a scalable process. In both cases, negative differential resistances with large peak current densities are achieved. [ABSTRACT FROM AUTHOR]

Highlights • In-plane InGaAs nanowires are grown using selective area molecular beam epitaxy. • Growth selectivity is achieved at 470 °C thanks to an atomic hydrogen flux. • High quality InGaAs thin films grown on InP without a buffer layer are achieved. Abstract We investigate the optical and electrical properties of InGaAs thin films and nanostructures grown directly on an InP semi-insulating substrate without any buffer layer using atomic hydrogen assisted molecular beam epitaxy. We confirm the positive influence of the atomic hydrogen flux during the deoxidization process as well as during the growth itself improving the photoluminescence properties of InGaAs quantum wells. We also study the effect of the atomic hydrogen flux on the electrical properties of buffer free undoped, Te or Si doped InGaAs epilayers. Eventually, we demonstrate that atomic hydrogen flux can be used to achieve InGaAs growth selectivity with respect to a SiO 2 mask for a growth temperature as low as 470 °C and obtain in-plane InGaAs nanostructures on InP with good transport properties. [ABSTRACT FROM AUTHOR]

The low responsivity of the low-temperature-grown GaAs based planar photoconductors used in the photomixing experiments can be improved by using a metal-metal Fabry-Pérot cavity. This resonant cavity photoconductor exhibits a dc-responsivity above 0.1 A/W and current density higher than 50 kA/cm2 with a low-temperature-grown-GaAs epitaxial layer presenting a subpicosecond carrier lifetime. Based on these results, up to 100 μW output power at 1 THz could be expected if this photoconductor is used in a photomixing experiment with a resonant antenna. [ABSTRACT FROM AUTHOR]

The strain relaxation in low mismatched InxAl1-xAs layers has been studied by triple axis x-ray diffraction, transmission electron microscopy, and photoluminescence. Using a two step buffer, a fully relaxed top layer has been grown by adapting the composition and thickness of a first “strained layer.” The threading dislocation density in the top layer is below 106/cm2 and strain is relaxed at the substrate/first layer interface by misfit dislocations. This scheme is a promising method to limit the thickness of buffer layers and obtain fully relaxed pseudosubstrates. [ABSTRACT FROM AUTHOR]

The authors show in this Letter that photoconductors based on GaAs grown at low temperatures can exhibit photoresponses as high as 25 mA/W under continuous-wave 1550-nm-wavelength illumination. It is achieved by using an optical Fabry–Pérot cavity in order to improve the external quantum efficiency and by decreasing the post-growth annealing temperature down-to 450°C. [ABSTRACT FROM AUTHOR]

We report on the epitaxial growth of high electron mobility AlSb/InAs heterostructure on exactly oriented (001) Si substrate, using a GaP interfacial layer. The growth conditions are first optimized on GaP substrates to achieve the highest electron mobility. The influence of the Sb flux during the early stage of the GaSb buffer layer is particularly emphasized. Using these optimized growth conditions, the AlSb/InAs heterostructure is grown on a GaP/Si template obtained by metal-organic vapor phase epitaxy. An electron mobility as high as 27 800 cm2 V-1 s-1 and 111 000 cm2 V-1 s-1, respectively, at 300 and 77 K is demonstrated. [ABSTRACT FROM AUTHOR]

We report a high maximum frequency of oscillation (${f} _{\text {max}}$) and a current-gain cutoff frequency (${f} _{\text {T}}$) of 800 and 260 GHz, respectively, with pseudomorphic high-electron mobility transistor (PHEMT), using an InGaAs/InAs composite channel and an asymmetric gate recess. This result was achieved with long gate length ${L} _{\text {G}} = {75}$ nm. The RF small signal equivalent circuit (SSEC) was extracted up to 110 GHz. Moreover, noise parameters extraction gives a minimum noise figure (NFmin) of 0.8 dB (with associated gain ${G} _{\text {ass}} = {16}$ dB) and 1.8 dB (with associated gain ${G} _{\text {ass}} = {11.6}$ dB) at 40 and 94 GHz, respectively. In this study, the gate leakage current was considered in the SSEC of the transistor (${g} _{\text {gf}}$ and ${g} _{\text {df}}$) and for extraction of the noise parameters. [ABSTRACT FROM AUTHOR]

We report on the epitaxial growth of an AlSb/InAs heterostructure on a (001) GaP substrate. We investigate the conditions for the most efficient relaxation of GaSb islands on GaP. In particular, we show that the GaP surface treatment and the growth temperature are crucial for the formation of a two-dimensional periodic array of 90° misfit dislocations at the episubstrate interface. With this relaxation process, an AlSb/InAs heterostructure exhibiting a room temperature mobility of 25 500 cm2 V-1 s-1 on GaP is demonstrated. This result paves the way to the integration of Sb-based devices on Si substrates through the use of GaP/Si templates. [ABSTRACT FROM AUTHOR]

The achievement of single‐channel 100 Gbit/s transmission, using linear unitravelling carrier photodiodes and QAM‐16 modulation format is reported. The wireless link has been done in the indoor case, considering the recent frequency standardised 300 GHz bands. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

It is shown from accurate on-wafer measurement that continuous wave output powers of 1.2 mW at 50 GHz and 0.35 mW at 305 GHz can be generated by photomixing in a low temperature grown GaAs photoconductor using a metallic mirror Fabry-Pérot cavity. The output power is improved by a factor of about 100 as compared to the previous works on GaAs photomixers. A satisfactory agreement between the theory and the experiment is obtained in considering both the contribution of the holes and the electrons to the total photocurrent. [ABSTRACT FROM AUTHOR]

The achievement of single-channel 100 Gbit/s transmission, using linear unitravelling carrier photodiodes and QAM-16 modulation format is reported. The wireless link has been done in the indoor case, considering the recent frequency standardised 300 GHz bands. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]