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Carrier reduction studies of type-II superlattice materials for very long wavelength infrared sensing
摘要： There are continuing efforts to develop type-II superlattice (SL) materials for very long wavelength infrared (VLWIR) detector applications. However, the SLs have high residual electron background doping densities that depend on SL growth conditions, which lead to shorter minority carrier lifetime and lower performance parameters than theoretically predicted. In this study, the authors compare the technical advantages of using InAs/GaInSb over InAs/GaSb SL with respect to reducing the electron doping levels. Our temperature-dependent electrical transport measurements show that the InAs/GaInSb SL design has a lower electron density than the InAs/GaSb SL with the same bandgap and have electron densities (mobilities) on the order of the mid 1011 cm?2 (25 000 cm2/V s). Since small period InAs/GaInSb SLs also produce greater Auger recombination suppression for a given VLWIR gap than the large period InAs/GaSb SL, the InAs/GaInSb SL appears to be a better candidate for long lifetime IR materials for future very long wavelength infrared devices.
关键词： very long wavelength infrared,mobility,InAs/GaSb,Auger recombination,InAs/GaInSb,type-II superlattice,carrier reduction,electron doping
更新于2025-09-19 17:15:36
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Real-Time Detection of Single Auger Recombination Events in a Self-Assembled Quantum Dot
摘要： Auger recombination is a non-radiative process, where the recombination energy of an electron-hole pair is transferred to a third charge carrier. It is a common effect in colloidal quantum dots that quenches the radiative emission with an Auger recombination time below nanoseconds. In self-assembled QDs, the Auger recombination has been observed with a much longer recombination time in the order of microseconds. Here, we use two-color laser excitation on the exciton and trion transition in resonance fluorescence on a single self-assembled quantum dot to monitor in real-time single quantum events of the Auger process. Full counting statistics on the random telegraph signal give access to the cumulants and demonstrate the tunability of the Fano factor from a Poissonian to a sub-Poissonian distribution by Auger-mediated electron emission from the dot. Therefore, the Auger process can be used to tune optically the charge carrier occupation of the dot by the incident laser intensity; independently from the electron tunneling from the reservoir by the gate voltage. Our findings are not only highly relevant for the understanding of the Auger process, it also demonstrates the perspective of the Auger effect for controlling precisely the charge state in a quantum system by optical means.
关键词： Auger recombination,Resonance fluorescence,Quantum dots,Full counting statistics,Random telegraph signal
更新于2025-09-19 17:13:59
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Auger Recombination in Quantum Well Laser with Participation of Electrons in Waveguide Region
摘要： A new mechanism of nonradiative recombination of nonequilibrium carriers in semiconductor quantum wells is suggested and discussed. For a studied Auger recombination process the energy of localized electron-hole pair is transferred to barrier carriers due to Coulomb interaction. The analysis of the rate and the coefficient of this process is carried out. It is shown, that there exists two processes of thresholdless and quasithreshold types, and thresholdless one is dominant. The coefficient of studied process is a non-monotonous function of quantum well width having maximum in region of narrow quantum wells. Comparison of this process with CHCC process shows that these two processes of nonradiative recombination are competing in narrow quantum wells, but prevail at different quantum well widths.
关键词： waveguide region,Auger recombination,nonradiative recombination,quantum well laser,semiconductor
更新于2025-09-16 10:30:52
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What limits the efficiency of GaN-based superluminescent light-emitting diodes (SLEDs)?
摘要： Gallium-nitride-based SLEDs are attractive light sources for augmented reality displays and other applications. However, the electrical-to-optical power conversion efficiency (PCE) of SLEDs is still far below the record-high values reported for LEDs. Utilizing advanced numerical device simulation, this paper investigates the internal physical pro- cesses that cause the low PCE of SLEDs. The poor hole conductivity strongly reduces the electrical efficiency, similar to laser diodes. However, in contrast to laser diodes, the rising carrier density in the active layers is identified as main reason for enhanced Auger recom- bination that severely limits the internal quantum efficiency. Design improvement options are demonstrated.
关键词： Superluminescent light-emitting diode,Auger recombination,InGaN/GaN,Laser diode,Self-heating,Power conversion efficiency,SLED,Hole conductivity
更新于2025-09-12 10:27:22
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Evidence of trap-assisted Auger recombination in low radiative efficiency MBE-grown III-nitride LEDs
摘要： By studying low radiative e?ciency blue III-nitride light emitting diodes (LEDs), we ?nd that the ABC model of recombination commonly used for understanding e?ciency behavior in LEDs is insu?cient and that additional e?ects should be taken into account. We propose a modi?cation to the standard recombination model by incorporating a bimolecular nonradiative term. The modi?ed model is shown to be in much better agreement with the radiative e?ciency data and to be more consistent than the conventional model with very short carrier lifetimes measured by time-resolved photoluminescence in similar, low radiative e?ciency material. We present experimental evidence that a hot carrier-generating process is occurring within these devices, in the form of measurements of forward photocurrent under forward bias. The forward photocurrent, due to hot carrier generation in the active region, is present despite the lack of any “e?ciency droop”—the usual signature of band-to-band Auger recombination in high-quality III-nitride LEDs. Hot carrier generation in the absence of band-to-band Auger recombination implies that some other source of hot carriers exists within these low radiative e?ciency devices, such as trap-assisted Auger recombination.
关键词： hot carrier generation,III-nitride LEDs,ABC model,trap-assisted Auger recombination,radiative efficiency
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Activated Auger Processes and their Wavelength Dependence in Type-I Mid-Infrared Laser Diodes
摘要： Type-I quantum well (QW) lasers based on the GaSb material system show attractive characteristics in the mid-infrared [1]. However, as the wavelength (λ) increases in the range of 2-4 μm their performance begins to deteriorate due to increasing Auger recombination [2]. In the Auger process, the energy released from an electron-hole recombination is transferred to a third carrier. In order to develop strategies to suppress Auger recombination, it is crucial to understand the magnitude and nature of the dominant Auger recombination pathway, and their dependencies on the operating λ and temperature (T). In QW structures two fundamentally different Auger process can occur [3]. In an activated Auger process, initial and final carrier states are confined to the plane of the QW. The recombination rate due to this process depends exponentially on T because it is determined by an activation energy, which is a consequence of energy and momentum conservation. In a thresholdless Auger process, the initial carrier states can exist near the band edge (bottom of conduction/valence band) and the third carrier is excited into the continuum of unbound states in a direction perpendicular to the plane of the well. Without an activation energy, the thresholdless Auger process exhibits only a weak T dependence. In this work, we report on the T and λ dependence of the threshold current density (Jth) of type-I QW devices operating in range 1.95-3.2 μm. From T-dependent measurements, we find that radiative recombination dominates from low T up to a break point temperature [4]. Beyond this break point the temperature sensitivity of Jth increases rapidly, indicating the onset of a strongly temperature-sensitive activated Auger process. Using hydrostatic pressure, we tune the operating λ of the lasers in order to probe the λ dependence of the Auger coefficient. Modelling the gain and loss characteristics of the lasers allowed the threshold carrier density (nth) to be determined. Since the carrier density calculations depend sensitively on the threshold gain, we undertook segmented contact measurements to experimentally determine the optical loss. By extracting the experimentally-determined radiative component of Jth and assuming the remaining non-radiative current (cid:1836)(cid:1866)(cid:1870)=(cid:1829)(cid:1866)(cid:1872)?, C and its λ dependence were calculated, although the analysis also provides evidence that the dependence is not strictly cubic (i.e., C depends on nth).
关键词： temperature dependence,Type-I quantum well lasers,Auger recombination,mid-infrared,wavelength dependence,GaSb material system
更新于2025-09-12 10:27:22
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Alloy-assisted Auger recombination in InGaN
摘要： It has been numerically investigated the effect of alloying on the Auger recombination rate in wurtzite type n-InGaN. In order to explicitly take into account the effect of alloy disorder, the calculations have been performed with a 256-atom supercell that includes In and Ga atoms randomly distributed over the supercell sites to obtain a given composition. A full band structure (no band scissors-shifting) and high-dense inhomogeneous k-point grid were used to improve the accuracy of the calculations. We show that the large number of allowed interband Auger transitions originated by the breaking of the translational periodicity plays a crucial role in the wide band gap InGaN alloys. The alloy-assisted Auger coefficients for these alloys are in the 1.0 × 10?32–4.7 × 10?31 cm6/s range
关键词： InGaN alloys,Atomic disorder,Supercell,Auger recombination
更新于2025-09-09 09:28:46
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Theoretical Study of Auger Recombination of Excitons in Monolayer Transition-metal Dichalcogenides
摘要： Excitons are the most prominent features of the optical properties of monolayer transition-metal dichalcogenides(TMDC). In view of optoelectronics it is very important to understand the decay mechanisms of the excitons of these materials. Auger recombination of excitons are regarded as one of the dominant decay processes. In this paper the Auger constant of recombination is computed based on the approach proposed by Kavoulakis and Baym. We obtain both temperature dependent (from type A, A’ processes) and temperature independent (from type B, B’ processes) contributions, and a numerical estimate of theoretical result yields the value of constant in the order of 10?2 cm2s?1, being consistent with existing experimental data. This implies that Auger decay processes severely limit the photoluminescence yield of TMDC-based optoelectronic devices.
关键词： Auger recombination,Transition-metal dichalcogenides,Exciton
更新于2025-09-04 15:30:14