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We experimentally investigate Andreev transport through the interface between an indium superconductor and the edge of the InAs/GaSb bilayer. To cover all possible regimes of InAs/GaSb spectrum, we study samples with 10-nm, 12 nm, and 14 nm thick InAs quantum wells. For the trivial case of a direct band insulator in 10 nm samples, differential resistance demonstrates standard Andreev reflection. For InAs/GaSb structures with band inversion (12 nm and 14 nm samples), we observe distinct low-energy structures, which we regard as direct evidence for the proximity-induced superconductivity within the current-carrying edge state. For 14 nm InAs well samples, we additionally observe mesoscopic-like resistance fluctuations, which are subjected to threshold suppression in low magnetic fields.

Energy relaxation dynamics in vertically coupled multi-stacked InAs/GaAs quantum dots Applied Physics Letters 110, 033107 (2017); 10.1063/1.4974221 High saturation intensity in InAs/GaAs quantum dot solar cells and impact on the realization of the intermediate band concept at room-temperature Applied Physics Letters 110, 061107 (2017); 10.1063/1.4975478 Stress-determined nucleation sites above GaAs-capped arrays of InAs quantum dots

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Low-temperature grown GaAs films with indium delta layers are studied by transmission electron microscopy. The delta layers in the as-grown film are found to be as thick as four monolayers ͑ML͒ independently of a nominal In deposit of 0.5 or 1 ML, a thickness which reflects the film surface roughness during the low-temperature growth. A pronounced In-Ga intermixing is observed in the films subjected to 500-700°C isochronal anneals. The In-Ga interdiffusion diffusivity is evaluated. The effective activation energy for In-Ga interdiffusion is found to be 1.1Ϯ0.3 eV which is significantly smaller than a value of 1.93 eV for a stoichiometric GaAs. The difference seems to result from a loss of the gallium vacancy supersaturation upon annealing, and is consistent with an annihilation enthalpy of 0.8 eV.

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The atomic structure and energy spectrum of Ga(As,P)/GaP heterostructures were studied. It was shown that the deposition of GaAs of the same nominal thickness leads to the formation of pseudomorphic GaAs/GaP quantum wells (QW), fully relaxed GaAs/GaP self-assembled quantum dots (SAQDs), or pseudomorphic GaAsP/GaP SAQDs depending on the growth temperature. We demonstrate that the atomic structure of Ga(As,P)/GaP heterostructures is ruled by the temperature dependence of adatom diffusion rate and GaAs-GaP intermixing. The band alignment of pseudomorphic GaAs/GaP QW and GaAsP/GaP SAQDs is shown to be of type II, in contrast to that of fully relaxed GaAs/GaP SAQDs, which have the band alignment of type I with the lowest electronic states at the indirect L valley of the GaAs conduction band.

A high-power, diode-pumped, semiconductor saturable absorber mode-locked Yb(5%):KGW bulk laser was demonstrated with high optical-to-optical efficiency. Average output power as high as 8.8 W with optical-to-optical efficiency of 37.5% was obtained for Nm-polarized laser output with 162 fs pulse duration and 142 nJ pulse energy at a pulse repetition frequency of 62 MHz. For Np polarization, 143 fs pulses with pulse energy of 139 nJ and average output power of up to 8.6 W with optical-to-optical efficiency of 31% were generated.