Capture of photoexcited carriers in a single quantum well with different confinement structures

Morin, S.; Deveaud, B.; Clérot, Fabrice; Fujiwara, K.; Mitsunaga, K.

doi:10.1109/3.89991

Cited by 82 publications

(22 citation statements)

References 24 publications

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“…Reduction in the overall capture time in QWs was also observed by Morin et al, 11 who studied the capture of photoexcited carriers into GaAs/AlGaAs QWs embedded in various types of graded confinement layers ͑used in typical laser structures͒. They found that carrier capture was appreciably shorter for QWs confined in the graded structures then those in the uniform ͑ungraded͒ structures.…”

Section: ͓S0003-6951͑98͒01849-x͔supporting

confidence: 49%

“…1 Since diffusion and drift correctly describe the motion and capture of carriers in QWs with thick barriers, 10 the internal electric fields ͑i.e., concentration gradients͒ play a crucial role in the dynamics of carriers. The carriers in the intermixed QW are accelerated toward the well by the quasielectric fields produced by the composition gradients 10,11 and this additional ''pull'' is responsible of the reduction of the overall capture times.…”

Section: ͓S0003-6951͑98͒01849-x͔mentioning

confidence: 99%

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Improved carrier collection in intermixed InGaAs/GaAs quantum wells

Dao

Johnston

Gál

et al. 1998

Applied Physics Letters

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We have used photoluminescence up conversion to study the carrier capture times into intermixed InGaAs/GaAs quantum wells. We have found that the capture into the intermixed wells is markedly faster than capture into the reference ͑unintermixed͒ quantum wells. The reasons for the significant reduction in the capture time is related to the shape of the intermixed quantum well. Such a reduction in the capture time is beneficial both in terms of the quantum efficiency and the frequency response of intermixed optoelectronic devices. © 1998 American Institute of Physics. ͓S0003-6951͑98͒01849-X͔Quantum well intermixing ͑QWI͒ is a method of considerable recent interest due to its wide applicability in optoelectronics. 1 QWI is based on the modification of the shape of the quantum well, and allows the post growth adjustment of several key parameters, such as the effective band gap, the optical absorption coefficient, and the refractive index. This flexibility enables the monolithic integration of optoelectronic devices, such as lasers, modulators, waveguides, amplifiers, etc. onto a single chip. 2 QWI has also been used to fabricate blueshifted 3 and multiplewavelength laser diodes, low threshold lasers, and lasers with saturable absorbers, in addition to improving the performance of high power lasers. 1 In this letter, we shall show that in addition to modifying the quantum well parameters mentioned above, QWI can also have a significant impact on the carrier capture into ͑intermixed͒ quantum wells. We shall show that in intermixed InGaAs/GaAs quantum wells, the carrier capture is faster than in similar but nonintermixed quantum wells. This efficient carrier capture can explain the relatively high quantum efficiency of intermixed light emitting devices, and may also result in improved frequency response of optoelectronic devices in general. The carrier capture times were determined from time resolved photoluminescence measurements using the photoluminescence up-conversion technique.The photoluminescence ͑PL͒ up-conversion experiments 4 were performed using a femtosecond self-mode locked Ti:sapphire laser, using a LiIO 3 nonlinear crystal. The laser was tunable between 750 and 900 nm, the pulse width was 80 fs, the repetition rate 85 MHZ, and the output power was 200 mW at ϭ780 nm. The time resolution of our system was approximately 200 fs. The optically excited carrier concentration was approximately 4ϫ10 10 carriers/cm 2 . The samples were mounted in a variable temperature, closed cycle, He cryostat, the temperature of which could be varied between 8 and 300 K. In this study we shall discuss results obtained on a number of In x Ga 1Ϫx As/GaAs quantum well ͑QW͒ samples grown by metalorganic chemical vapor deposition. Each sample contained two QWs: a 5-nm-wide In 0.15 Ga 0.85 As well and a 5-nm-wide In 0.3 Ga 0.7 As well embedded between 50-nm-thick GaAs barriers. To achieve intermixing, we used room temperature proton implantation in combination with rapid thermal annealing ͑RTA͒. Details of the implantation conditions...

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Section: ͓S0003-6951͑98͒01849-x͔supporting

confidence: 49%

Section: ͓S0003-6951͑98͒01849-x͔mentioning

confidence: 99%

Improved carrier collection in intermixed InGaAs/GaAs quantum wells

Dao

Johnston

Gál

et al. 1998

Applied Physics Letters

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“…at different temperatures, carrier densities, well and barrier widths, etc). These include static [10,11,38] and time-resolved [7,[12][13][14][15][16][17][18][19] photoluminescence, pump-probe spectroscopy [20][21][22] and modulation response measurements [23][24][25][26]. The estimated values for the capture lifetime reported in these works vary over a wide range, from several hundreds of femtoseconds to several tens of picoseconds, which is only partly justified by the differences among the samples studied.…”

Section: The Intrinsic Capture Lifetimementioning

confidence: 99%

“…A remarkable result of these early studies was the prediction of an oscillatory dependence of the capture rate on the QW width. The large body of experimental work that followed [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], based on several different techniques, found measured values for the capture lifetime varying over a wide range, from a fraction to tens of picoseconds, depending on the experimental conditions. Similarly, the predicted oscillations with well width were only observed under appropriate conditions [10,18,21], most notably in the low carrier density regime, where the lifetime broadening of the delocalized single-particle states is small.…”

Section: Introductionmentioning

confidence: 99%

Quantum-well capture and interwell transport in semiconductor active layers

Paiella

Hunziker

Vahala

1999

Semicond. Sci. Technol.

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Abstract. The dynamics of electrons and holes in multiquantum-well semiconductor gain media involves several different transport processes, such as diffusion and drift across the barrier region, as well as capture and escape transitions between the bound and the unbound states of the quantum wells. In addition to their fundamental interest, these processes are important because of their implications for the dynamic properties of multiquantum-well lasers and optical amplifiers. Experimentally, they have been studied with several time-domain optical techniques having (sub)picosecond resolution and, more recently, with frequency-domain techniques based on laser modulation measurements. This article gives a brief review of the work done in this area and then presents in detail a frequency-domain approach, four-wave mixing spectroscopy in semiconductor optical amplifiers, to investigate intrinsic capture and interwell equilibration. This technique allows one to extend the device modulation frequency to several hundreds of gigahertz, thus providing the required time resolution, and can be configured to isolate and directly study the transport process of interest.

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“…Existence of multiple quantized states will complicate the model due to the intersubband transitions and is currently under investigation. We consider the electron capture process only, assuming that the quantum capture of electrons is slower or the capture process is ambipolar [Morin 1991, Eisenstein 1991. However, the same formulism can be applied in the study of hole capture.…”

Section: Ring-chmentioning

confidence: 99%

Intrinsic, P-Doped and Modulation-Doped Quantum Well Lasers for Ultrafast Modulation and Ultrashort Pulses

Lau¹

1992

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Capture of photoexcited carriers in a single quantum well with different confinement structures

Cited by 82 publications

References 24 publications

Improved carrier collection in intermixed InGaAs/GaAs quantum wells

Improved carrier collection in intermixed InGaAs/GaAs quantum wells

Quantum-well capture and interwell transport in semiconductor active layers

Intrinsic, P-Doped and Modulation-Doped Quantum Well Lasers for Ultrafast Modulation and Ultrashort Pulses

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