Low-threshold continuous-wave two-stack quantum-dot laser with reduced temperature sensitivity

Shchekin, O.B.; Park, G.; Huffaker, Diana L.; Mo, Q.; Deppe, D.G.

doi:10.1109/68.874208

Cited by 51 publications

(13 citation statements)

References 11 publications

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“…4,5,6,7 Recent studies of electron spin dynamics in neutral QDs 4,5,8 have revealed that the discrete energy levels in quantum dots arising from three-dimensional quantum confinement blocks the dominant spin relaxation channels present in higher dimensional bulk and quantum well systems, resulting in considerably longer spin relaxation times. Combined with the high optical luminescence efficiency observed in QDs, 9,10,11 these long spin relaxation times should lead to larger spin-dependent luminescence signatures in spin detection applications incorporating QDs as an optical marker. The first spin LED using neutral QDs was recently demonstrated.…”

mentioning

confidence: 99%

Efficient electron spin detection with positively charged quantum dots

Gündoğdu

Hall

Boggess

et al. 2004

Applied Physics Letters

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We report the application of time-and polarization-resolved photoluminescence up-conversion spectroscopy to the study of spin capture and energy relaxation in positively and negatively charged, as well as neutral, InAs self-assembled quantum dots. When compared to the neutral dots, we find that carrier capture and relaxation to the ground state is much faster in the highly charged dots, suggesting that electron-hole scattering dominates this process. The long spin lifetime, short capture time, and high radiative efficiency of the positively charged dots, indicates that these structures are superior to both quantum well and neutral quantum dot light-emitting diode (LED) spin detectors for spintronics applications.The efficient detection of spin-polarized carriers is a crucial issue for the design of semiconductor-based spintronic devices. 1 A light-emitting diode (LED) configuration employing a quantum well as an optical marker has proven to be an effective means of detecting spin polarized carriers. 2,3 In a spin LED, the degree of circular polarization of the quantum well luminescence provides a direct measure of the spin polarization of the carriers arriving at the spatial location of the quantum well.The application of semiconductor quantum dots (QDs) in such a spin detection scheme is expected to provide a substantial improvement in spin sensitivity over the use of a quantum well. 4,5,6,7 Recent studies of electron spin dynamics in neutral QDs 4,5,8 have revealed that the discrete energy levels in quantum dots arising from three-dimensional quantum confinement blocks the dominant spin relaxation channels present in higher dimensional bulk and quantum well systems, resulting in considerably longer spin relaxation times. Combined with the high optical luminescence efficiency observed in QDs, 9,10,11 these long spin relaxation times should lead to larger spin-dependent luminescence signatures in spin detection applications incorporating QDs as an optical marker. The first spin LED using neutral QDs was recently demonstrated. 6 Few experiments have examined electron spin dynamics in charged quantum dots. 12,13 Through a comparison of spin capture and relaxation dynamics in neutral, positively (+QDs) and negatively (-QDs) charged QDs, we demonstrate that +QDs act as a highly efficient detector for spin-polarized electrons. Our room temperature time-resolved measurements reveal that, following capture of spin-polarized electrons, the initial degree of circular polarization of the QD ground state luminescence is more than four times larger in +QDs compared to neutral QDs. The larger spin signature in +QDs originates from an increased rate of capture of spin polarized electrons through interaction with the built-in hole population, 14,15 as indicated by the early time dynamics of the QD photoluminescence. Rapid electron capture into +QDs reduces spin relaxation in the GaAs barriers prior to capture, resulting in a six-fold enhancement in the time-integrated spin detection efficiency with the incorporation of positiv...

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mentioning

confidence: 99%

Efficient electron spin detection with positively charged quantum dots

Gündoğdu

Hall

Boggess

et al. 2004

Applied Physics Letters

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“…Lower RT CW I th values of 1.2 and 1.25 mA have been reported for narrower oxide-confined QD lasers with HR facet coatings. 4,14 However, the maximum output powers achieved for these devices were very low, with values of 290 and 350 µW. 4,14 The RT threshold current density can be reduced further by increasing the cavity length to 2 mm.…”

Section: Effects Of Hr Coating On the Performance Of 13-µm Qd Lasersmentioning

confidence: 98%

High performance 1.3μm InAs/GaAs quantum dot lasers with low threshold current and negative characteristic temperature

et al. 2006

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A high-growth-temperature step used for the GaAs spacer layer is shown to significantly improve the performance of 1.3-µm multilayer InAs/GaAs quantum-dot (QD) lasers. The high-growth-temperature spacer layer inhibits threading dislocation formation, resulting in enhanced electrical and optical characteristics and hence improved laser performance. The combination of high-growth-temperature GaAs spacer layers and high-reflectivity (HR) coated facets has been utilized to further reduce the threshold current and threshold current density (J th ) for 1.3-µm InAs/GaAs QD lasers. Very low continuous-wave room-temperature threshold current of 1.5 mA and a threshold current density of 18.8 A/cm 2 are achieved for a 3-layer device with a 1-mm long HR/HR cavity. For a 2-mm cavity the continuous-wave threshold current density is as low as 17 A/cm 2 at room temperature for an HR/HR device. An output power as high as 100 mW is obtained for a device with HR/cleaved facets. The high-growth-temperature spacer layers have only a relatively small effect on the temperature stability of the threshold current above room temperature. To further increase the characteristic temperature (T 0 ) of the QD lasers, 1.3-µm InAs/GaAs QD lasers incorporating p-type modulation doping have been grown and studied. A negative T 0 and J th of 48 A/cm -2 at room temperature have been obtained by combining the high-growth-temperature GaAs spacer layers with the p-type modulation doping of the QDs.

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“…Quantum dots offer significant advantages for future optoelectronic devices due to their reduced density of states [1], lower threshold currents [2], extended emission wavelength range [3,4], increased differential efficiency [5], and resistance to the negative impacts of thermal effects [2,6]. Research on quantum dots to date has focused primarily on self-assembly techniques which use the naturally occurring strain energy present in mismatched epitaxial growth to drive the formation of three dimensional structures.…”

Section: Introductionmentioning

confidence: 99%

Spectral and threshold performance of patterned quantum dot lasers

Elarde

Coleman

2006

Phys. Status Solidi (c)

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Semiconductor quantum dots have been widely researched as a means of improving the performance of optoelectronic devices. Self-assembly has been the dominant method of fabricating quantum dots because of its relative ease compared to more explicit techniques. We have developed a method for fabricating quantum dots in a more explicit manner using electron beam lithography and selective-area metal-organic chemical vapor deposition crystal growth. By eliminating the dependence on strain-driven self-assembly, we can avoid the size distribution and resulting inhomogeneously broadened emission spectrum associated with self-assembled quantum dot ensembles. We report on the threshold and spectral properties of patterned quantum dot lasers.

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Low-threshold continuous-wave two-stack quantum-dot laser with reduced temperature sensitivity

Cited by 51 publications

References 11 publications

Efficient electron spin detection with positively charged quantum dots

Efficient electron spin detection with positively charged quantum dots

High performance 1.3μm InAs/GaAs quantum dot lasers with low threshold current and negative characteristic temperature

Spectral and threshold performance of patterned quantum dot lasers

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