The lowest room-temperature threshold current density, 26A/cm 2 , of any semiconductor diode lasers is reported for a quantum dot device with a single InAs dot layer contained within a strained In 0.15 Ga 0.85 As quantum well. The lasers are epitaxially grown on a GaAs substrate, and the emission wavelength is 1.25 µ m.

We demonstrate stable, single-frequency output from single, as-fabricated GaN nanowire lasers operating far above lasing threshold. Each laser is a linear, double-facet GaN nanowire functioning as gain medium and optical resonator, fabricated by a top-down technique that exploits a tunable dry etch plus anisotropic wet etch for precise control of the nanowire dimensions and high material gain. A single-mode linewidth of ~0.12 nm and >18 dB side-mode suppression ratio are measured. Numerical simulations indicate that single-mode lasing arises from strong mode competition and narrow gain bandwidth.

The authors report an enhanced infrared spectral response of GaAs-based solar cells that incorporate type II GaSb quantum dots ͑QDs͒ formed using interfacial misfit array growth mode. The material and devices, grown by molecular beam epitaxy, are characterized by current-voltage and spectral response characteristics. From 0.9 to 1.36 m, these solar cells show significantly more infrared response compared to reference GaAs cells and previously reported InAs QD solar cells. The short circuit current density and open circuit voltages of solar cells with and without dots measured under identical conditions are 1.29 mA/ cm 2 , 0.37 V and 1.17 mA/ cm 2 , 0.6 V, respectively.

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Semiconductor ultralow-threshold InAs quantum-dot lasers are investigated operating at 1230–1250 nm at room temperature (laser threshold range is of 16–83 A/cm2 for ground-state emission). The dependence of gain on current is derived from measurements of the threshold current as a function of the cavity length. The ground-state gain appears at very low current: the inversion threshold of ∼13 A/cm2 is a record low value. Analysis of these data for diodes of different molecular beam epitaxial-grown wafers leads to a squared dipole moment of the transition of ∼9.2×10−57 C2 m2 that corresponds to the length of elementary dipole of ∼0.6 nm.

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We report optical, electrical, and spectral response characteristics of three-stack InAs∕GaAs quantum dot solar cells with and without GaP strain compensation (SC) layers. The short circuit current density, open circuit voltage, and external quantum efficiency of these cells under air mass 1.5G at 290mW∕cm2 illumination are presented and compared with a GaAs control cell. The cells with SC layers show superior device quality, confirmed by I-V and spectral response measurements. The quantum dot solar cells show an extended photoresponse compared to the GaAs control cell. The effect of the SC layer thickness on device performance is also presented.