Effects of the carrier relaxation lifetime and inhomogeneous broadening on the modulation response of InGaAs/GaAs self-assembled quantum-dot lasers

Fali, Alireza; Rajaei, Esfandiar; Kaftroudi, Zahra Danesh

doi:10.3938/jkps.64.16

Cited by 8 publications

(5 citation statements)

References 18 publications

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“…in which and respectively denote the number of carriers and photons in level i. is the spontaneous recombination time, is the photon lifetime into cavity [18], 0 − 2 is the initial capture time to 2 , and 0 2 − 1 0 1 − are initial relaxation times respectively to 2 and GS. Also,…”

Section: Fig 3: Schematics Of Carrier Transitions In Three-level Modmentioning

confidence: 99%

“…The time is dependent on the probability of occupation of origin and destination levels, requirements of Pauli Exclusion Principle, phonon bottleneck effect, etc; all the times are very short (~ps-ns) [40]. By taking into account all the transitions shown in the figure, and considering the homogeneous and inhomogeneous broadening, and nonlinear gain, the rate equations can be written as follow: (11) in which 𝑁 𝑖 and 𝑆 𝑖 respectively denote the number of carriers and photons in level i. 𝜏 𝑠𝑝 is the spontaneous recombination time, 𝜏 𝑠 is the photon lifetime into cavity [18], 𝜏 0𝑤𝑙−𝐸𝑆 2 is the initial capture time to 𝐸𝑆 2 , and 𝜏 0𝐸𝑆 2 −𝐸𝑆 1 𝑎𝑛𝑑 𝜏 0𝐸𝑆 1 −𝐺𝑆 are initial relaxation times respectively to 𝐸𝑆 2 and GS. Also,…”

Section: Iii-a Theoretical Modelmentioning

confidence: 99%

“…By changing the compositions, QDs can be engineered, and finding a way to enhance the efficiency of QDLs can be helpful. Many scientists are interested in 𝐼𝑛 𝑥 𝐺𝑎 1−𝑥 𝐴𝑠/GaAs QD laser devices due to their interesting and applicable features [4,12,13,17,18].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Indium-Percentage Variation on Dynamical Characteristics of InxGa1-xAs/GaAs(001) Quantum Dot Lasers

Borji

Rajaei

2016

Iran J Sci Technol Trans Sci

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The influence of indium percentage on dynamical characteristics of InxGa1-xAs/GaAs(001) quantum dot lasers (QDLs) is investigated. Energy levels of self-organized truncated-cone-shape QDs are calculated by means of the eight-band k.p model, and their dependence to indium percentage is surveyed. Then, by presenting a three-level model and numerical solution of the resulting rate equations, laser properties are determined. Our results show that inclusion of more indium gives rise in the reduced energy gap and electron-hole recombination energy. Moreover, lasing process for both Ground State (GS) and Excited States (ES) sound to be sensitive to indium percentage. It is shown that rise of indium percentage at fixed injected current results in the increased ES turn-on delay and GS photon number and 3dB modulation bandwidth, and decreased ES photon number, GS turn on delay, amplitude of relaxation oscillations, output power, and ES 3dB modulation bandwidth; but has no effect on threshold current and laser gain. At last, we find an optimized cavity length which was likely to be independent of indium percentage.

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Section: Fig 3: Schematics Of Carrier Transitions In Three-level Modmentioning

confidence: 99%

Section: Iii-a Theoretical Modelmentioning

confidence: 99%

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Influence of Indium-Percentage Variation on Dynamical Characteristics of InxGa1-xAs/GaAs(001) Quantum Dot Lasers

Borji

Rajaei

2016

Iran J Sci Technol Trans Sci

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“…A good knowledge of the carrier dynamics and recombination kinetics of InGaAs QWRs are of great importance to the design of the novel electronic devices. Recently, a large number of papers have reported on different characterization techniques to investigate the morphology [5], optical properties [6], and carrier dynamics [7] of InGaAs QWs, QWRs, and QDs grown on GaAs. Time-resolved photoluminescence with picosecond temporal resolution [8] and DLTS technique [9] were applied to study the carrier dynamics in presence of the quantum confined states, interface, and defect states introduced by sample preparation.…”

Section: Introductionmentioning

confidence: 99%

Charge carrier relaxation in InGaAs-GaAs quantum wire modulation-doped heterostructures

et al. 2017

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The time dependencies of the carrier relaxation in modulation-doped InGaAs-GaAs low-dimensional structures with quantum wires have been studied as functions of temperature and light excitation levels. The photoconductivity (PC) relaxation follows a stretched exponent with decay constant, which depends on the morphology of InGaAs epitaxial layers, presence of deep traps, and energy disorder due to inhomogeneous distribution of size and composition. A hopping model, where electron tunnels between bands of localized states, gives appropriate interpretation for temperature-independent PC decay across the temperature range 150-290 K. At low temperatures (T < 150 K), multiple trapping-retrapping via 1D states of InGaAs quantum wires (QWRs), sub-bands of two-dimensional electron gas of modulation-doped n-GaAs spacers, as well as defect states in the GaAs environment are the dominant relaxation mechanism. The PC and photoluminescence transients for samples with different morphologies of the InGaAs nanostructures are compared. The relaxation rates are found to be largely dependent on energy disorder due to inhomogeneous distribution of strain, nanostructure size and composition, and piezoelectric fields in and around nanostructures, which have a strong impact on efficiency of carrier exchange between bands of the InGaAs QWRs, GaAs spacers, or wetting layers; presence of local electric fields; and deep traps.

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“…Thus, finding a way to enhance the efficiency of QDLs can be helpful. Among many materials, In(Ga)As/GaAs laser devices are focused by many scientists due to their interesting and applicable features [4,10,11,16,17].…”

Section: Introductionmentioning

confidence: 99%

Impact of Dot Size on Dynamical Characteristics of InAs/GaAs Quantum Dot Lasers

Rajaei

Borji²

2017

Journal of Nanoelectronics and Optoelectronics

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The purpose of this research is to study laser dynamics of InAs/GaAs Quantum Dot Lasers (QDLs) by changing QD energy levels. To date, most of the investigations have focused on only one of these circumstances, and hardly the result of change in the energy levels can be seen in lasing. In this work, in the first step, energy levels of lens-shape QDs are investigated by the eight-band k.p method, their variation for different QD sizes are surveyed, and recombination energies of the discrete levels are determined. Then, by representing a three-level InAs/GaAs QD laser, dynamics of such a laser device is numerically studied by rate equations in which homogeneous and inhomogeneous broadenings are taken into account. The lasing process for both Ground State (GS) and Excited States (ES) was found to be much sensitive to the QD size. It was observed that in larger QDs, photon number and bandwidth of the small signal modulation decrease but turn-on delay, maximum output power, and threshold current of gain increase. It was also found that for a good modulation, smaller QDs, and form the point of view of high-power applications, larger QDs seem better.

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Effects of the carrier relaxation lifetime and inhomogeneous broadening on the modulation response of InGaAs/GaAs self-assembled quantum-dot lasers

Cited by 8 publications

References 18 publications

Influence of Indium-Percentage Variation on Dynamical Characteristics of InxGa1-xAs/GaAs(001) Quantum Dot Lasers

Influence of Indium-Percentage Variation on Dynamical Characteristics of InxGa1-xAs/GaAs(001) Quantum Dot Lasers

Charge carrier relaxation in InGaAs-GaAs quantum wire modulation-doped heterostructures

Impact of Dot Size on Dynamical Characteristics of InAs/GaAs Quantum Dot Lasers

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