Carrier transport and recombination in p-doped and intrinsic 1.3μm InAs∕GaAs quantum-dot lasers

Marko, Igor P.; Massé, N. F.; Sweeney, S. J.; Andreev, A. D.; Adams, A.R.; Hatori, Nobuaki; Sugawara, Mitsuru

doi:10.1063/1.2135204

Cited by 101 publications

(91 citation statements)

References 9 publications

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“…It has previously been suggested that the form of the carrier distribution changes around room temperature in the p-doped structures 4,11 and this may be the origin of the change in the gain that we observe. We examine this in Fig.…”

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confidence: 56%

“…͓DOI: 10.1063/1.2361167͔ p-type modulation doped In͑Ga͒As quantum dot lasers have attracted much interest recently, partially due to reports of an infinite or negative characteristic temperature ͑T 0 ͒ around room temperature. [1][2][3] Several authors have attributed this behavior to the temperature dependence of the Auger recombination process in doped structures, 2,4,5 although the particulars of the explanation varied in each case. In this work we report on measurements made on both intrinsic and p-doped quantum dot structures that emit at 1.3 m. From studying the radiative and nonradiative components of the threshold current we show that the temperature performance of p-doped lasers can be described without needing to consider Auger recombination.…”

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confidence: 99%

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Temperature dependence of threshold current in p-doped quantum dot lasers

Sandall

Smowton

Thomson

et al. 2006

Applied Physics Letters

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The authors measure the temperature dependence of the components of threshold current of 1300 nm undoped and p-doped quantum dot lasers and show that the temperature dependence of the injection level necessary to achieve the required gain is the largest factor in producing the observed negative T 0 in p-doped quantum dot lasers. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2361167͔ p-type modulation doped In͑Ga͒As quantum dot lasers have attracted much interest recently, partially due to reports of an infinite or negative characteristic temperature ͑T 0 ͒ around room temperature. 1-3 Several authors have attributed this behavior to the temperature dependence of the Auger recombination process in doped structures, 2,4,5 although the particulars of the explanation varied in each case. In this work we report on measurements made on both intrinsic and p-doped quantum dot structures that emit at 1.3 m. From studying the radiative and nonradiative components of the threshold current we show that the temperature performance of p-doped lasers can be described without needing to consider Auger recombination.Two samples were grown by solid source molecular beam epitaxy on 3 in. n + ͑100͒ GaAs substrates. The devices were nominally identical except for the level of modulation doping. The active region consisted of five dot-in-a-well ͑DWELL͒ repeats, where each DWELL was made up of 3.0 ML of InAs grown on 2 nm of In 0.15 Ga 0.85 As and then capped by a further 6 nm of In 0.15 Ga 0.85 As, and these were then separated by 50 nm GaAs spacers. The active region was incorporated into a GaAs-Al 0.4 Ga 0.6 As waveguide structure. The lower n-contact region was doped with Si at 5 ϫ 10 18 cm −3 while the upper p contact was doped with Be at 5 ϫ 10 17 cm −3 , the p contact was finished with a 300 nm layer of GaAs doped at 1 ϫ 10 19 cm −3 . The growth temperature for the cladding layers was 620°C, while the InAs layers were grown at 510°C, the GaAs spacers were grown in two temperature steps; the first 15 nm at 510°C and the final 35 nm at 580°C, forming the so called high growth temperature spacer layers. 6 The doping consisted of Be atoms incorporated over a 6 nm region of GaAs situated 9 nm below each DWELL at a concentration of either 0 or 7.5 ϫ 10 17 cm −3 corresponding to either 0 or 15 acceptor atoms per quantum dot. Previous work on these structures has shown that the absorption spectra, and therefore the quantum dot states, are the same for the two structures. 7The threshold current was measured as a function of temperature on 2000 m long, 50 m wide oxide stripe lasers for both structures under pulsed conditions with a pulse length of 400 ns and a repetition rate of 1 kHz to avoid any self-heating, and this is shown in Fig. 1. The undoped structure shows a monotonically increasing threshold current from low to high temperatures as is normally observed for undoped quantum dot and quantum well structures. The p-doped structure exhibits a threshold current density that decreases as the temperature increases from 200 K r...

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confidence: 56%

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confidence: 99%

Temperature dependence of threshold current in p-doped quantum dot lasers

Sandall

Smowton

Thomson

et al. 2006

Applied Physics Letters

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“…4 The lasing wavelength of the devices was approximately 1.28 m at room temperature. The active region consisted of ten stacked InAs dot-ina-well layers separated by either modulation p-doped or intrinsic GaAs barriers sandwiched by GaAs waveguide and AlGaAs cladding layers.…”

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confidence: 98%

“…5,6 Recent results reported that the superior thermal stability of InAs/ GaAs p-doped QD lasers around room temperature arises from a combination of improving thermal distribution of the electrons, leading to a decrease in the radiative current necessary to reach the lasing threshold, and an increase in nonradiative Auger recombination with temperature, together giving rise to a constant threshold current over a limited temperature range. 4 In this work, we consider the temperature sensitivity of the gain and specifically, the effect of the nonthermal distribution of the carriers on the gain characteristics of p-doped devices and compare the results to those obtained with intrinsic quantum dot lasers.The gain was measured using the method described by Hakki and Paoli 9 at both room temperature, where carriers in the intrinsic devices are in thermal equilibrium, and at 350 K, where carriers in the p-doped lasers are expected to be closer to thermal equilibrium. 4 The lasing wavelength of the devices was approximately 1.28 m at room temperature.…”

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Temperature dependence of the gain in p-doped and intrinsic 1.3μm InAs∕GaAs quantum dot lasers

Massé

Sweeney

Marko

et al. 2006

Applied Physics Letters

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The gain of p-doped and intrinsic InAs/ GaAs quantum dot lasers is studied at room temperature and at 350 K. Our results show that, although one would theoretically expect a higher gain for a fixed carrier density in p-doped devices, due to the wider nonthermal distribution of carriers amongst the dots at T = 293 K, the peak net gain of the p-doped lasers is actually less at low injection than that of the undoped devices. However, at higher current densities, p doping reduces the effect of gain saturation and therefore allows ground-state lasing in shorter cavities and at higher temperatures. Due to the large volume of data being readily transferred between network users, there is an increasing demand for "fiber-to-the-home" based optical fiber networks which require fast and temperature insensitive semiconductor lasers emitting at 1.3 m. Despite significant progress in reducing the threshold current densities ͑J th ͒ or improving the temperature stability, 1,2 intrinsic quantum dot ͑QD͒ lasers emitting around 1.3 m have yet to meet their full potential. This is attributed to many factors such as inhomogeneous broadening or size dispersion of the dots and dominating nonradiative recombination at room temperature ͑RT͒ which increases J th and its sensitivity to temperature variations. 3,4 It has been proposed that p-doping the devices and thus saturating the levels in the valence band with holes would greatly improve the device performance by increasing the gain and the bandwidth. 5,6 Although the effect of p-doping shows major improvements on the temperature sensitivity and the bandwidth of the devices, 7 measurements do not show a clear enhancement of the gain for a given injection 8 as it is expected from theory. 5,6 Recent results reported that the superior thermal stability of InAs/ GaAs p-doped QD lasers around room temperature arises from a combination of improving thermal distribution of the electrons, leading to a decrease in the radiative current necessary to reach the lasing threshold, and an increase in nonradiative Auger recombination with temperature, together giving rise to a constant threshold current over a limited temperature range. 4 In this work, we consider the temperature sensitivity of the gain and specifically, the effect of the nonthermal distribution of the carriers on the gain characteristics of p-doped devices and compare the results to those obtained with intrinsic quantum dot lasers.The gain was measured using the method described by Hakki and Paoli 9 at both room temperature, where carriers in the intrinsic devices are in thermal equilibrium, and at 350 K, where carriers in the p-doped lasers are expected to be closer to thermal equilibrium. 4 The lasing wavelength of the devices was approximately 1.28 m at room temperature. The active region consisted of ten stacked InAs dot-ina-well layers separated by either modulation p-doped or intrinsic GaAs barriers sandwiched by GaAs waveguide and AlGaAs cladding layers. The chips were driven with 50 s long pulses at a duty cycle of 50%. The...

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Quantum Dot Technologies

Hogg

Zhang

2014

The Physics and Engineering of Compact Quantum Dot‐based Lasers for Biophotonics

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Carrier transport and recombination in p-doped and intrinsic 1.3μm InAs∕GaAs quantum-dot lasers

Cited by 101 publications

References 9 publications

Temperature dependence of threshold current in p-doped quantum dot lasers

Temperature dependence of threshold current in p-doped quantum dot lasers

Temperature dependence of the gain in p-doped and intrinsic 1.3μm InAs∕GaAs quantum dot lasers

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