New photoluminescence effects of carrier confinement at an AlGaAs/GaAs heterojunction interface

Yuan, Y. R.; Pudensi, M. A. A.; Vawter, G.A.; Merz, J. L.

doi:10.1063/1.335692

Cited by 96 publications

(37 citation statements)

References 14 publications

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“…Probably, the very short range of the local Al-impurity potential does not extend into the bulk region where the exciton recombination is expected to take place. 18 It appears from Fig. 8 as if the PL ratio saturates at high mobilities.…”

Section: Photo Luminescence and 2deg Mobilitymentioning

confidence: 99%

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Photoluminescence and the gallium problem for highest-mobility GaAs/AlGaAs-based 2d electron gases

Schläpfer

Dietsche

Reichl

et al. 2016

Journal of Crystal Growth

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The quest for extremely high mobilities of 2d electron gases in MBE-grown heterostructures is hampered by the available purity of the starting materials, particularly of the gallium. Here we compare the role of different Ga lots having nominally the highest possible quality on the mobility and the photoluminescence (PL) of modulation doped single interface structures and find significant differences. A weak exciton PL reveals that the purity of the Ga is insufficient. No high mobility can be reached with such a lot with a reasonable effort. On the other hand, a strong exciton PL indicates a high initial Ga purity, allowing to reach mobilities of 15 million (single interface) or 28 million cm 2 /V sec (doped quantum wells) in our MBE systems. We discuss possible origins of the inconsistent Ga quality. Furthermore, we compare samples grown in different MBE systems over a period of several years and find that mobility and PL is correlated if similar structures and growth procedures are used.

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Section: Photo Luminescence and 2deg Mobilitymentioning

confidence: 99%

“…17 In a few samples we noticed that the (X) peak splits into two which could be a consequence of the 2DEG interacting with the exciton transition and might be connected with the H-band. 18 It seems that this feature is, however, not relevant for the analysis of the Ga quality.…”

Section: Characterizing Heterostructures By Photoluminescencementioning

confidence: 99%

Photoluminescence and the gallium problem for highest-mobility GaAs/AlGaAs-based 2d electron gases

Schläpfer

Dietsche

Reichl

et al. 2016

Journal of Crystal Growth

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“…Several effects have been reported, such as band bending at the interface leading to the accumulation of the charge at the interface or piezo electric strain. [23][24][25][26][27] In addition, the AlGaAs alloy typically used for capping GaAs nanowires is generally inhomogeneous, with directed and random segregation of Ga and Al forming respectively Al-rich ridges and Ga-rich nanoscale islands . 28,29 Simultaneously, III-V NWs can suffer from twin defects and polytypism, 30,31 which adversely affect their electronic and optical properties.…”

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confidence: 99%

“…24,26,27 For simple AlGaAs/GaAs the band bending at the interface forms a pocket for the electrons or holes . 23,49 Such confined carriers at the interface will recombine with the free carriers (of the opposite species) in the valence or conduction band at a sufficient distance from the interface that flat-band conditions have been re-established. As the charges are spatially separated, emission has a spatially indirect character and is red shifted in comparison to the simple excitonic emission observed in uncapped GaAs.…”

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confidence: 99%

Revealing Large-Scale Homogeneity and Trace Impurity Sensitivity of GaAs Nanoscale Membranes

et al. 2017

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III-V nanostructures have the potential to revolutionize optoelectronics and energy harvesting. For this to become a reality, critical issues such as reproducibility and sensitivity to defects should be resolved. By discussing the optical properties of MBE grown GaAs nanomembranes we highlight several features that bring them closer to large scale applications. Uncapped membranes exhibit a very high optical quality, 1 arXiv:1704.08477v1 [cond-mat.mes-hall] 27 Apr 2017 expressed by extremely narrow neutral exciton emission, allowing the resolution of the more complex excitonic structure for the first time. Capping of the membranes with an AlGaAs shell results in a strong increase of emission intensity but also to a shift and broadening of the exciton peak. This is attributed to the existence of impurities in the shell, beyond MBE-grade quality, showing the high sensitivity of these structures to the presence of impurities. Finally, emission properties are identical at the sub-micron and sub-millimeter scale, demonstrating the potential of these structures for large scale applications.Keywords: GaAs/AlGaAs nano mebranes, photoluminescence, electronic and optical properties of ensemble vs single nano membrane Nanowires (NWs) are filamentary crystals with a diameter in the sub-micrometer down to nanometer range. Their special morphology, dimensions and high surface-to-volume ratio are often translated into advantageous optical and electrical properties. As a consequence, they have been widely used in electronics, 1-5 optoelectronics, 6,7 solar cells 8-11 and sensors. 12,13 If not adequately passivated, the surface recombination can limit the optical performance of the NWs. 14 In addition, surface depletion can also affect the volume distribution and separation of the carriers in the NW. 15-19 Different passivation methods have been employed in the past, notably capping of the free surfaces with a higher bandgap shell around the nanowire. [20][21][22] Nevertheless, capping also modifies the nature of the surface. Several effects have been reported, such as band bending at the interface leading to the accumulation of the charge at the interface or piezo electric strain. [23][24][25][26][27] In addition, the AlGaAs alloy typically used for capping GaAs nanowires is generally inhomogeneous, with directed and random segregation of Ga and Al forming respectively Al-rich ridges and Ga-rich nanoscale islands . 28,29 Simultaneously, III-V NWs can suffer from twin defects and polytypism, 30,31 which adversely affect their electronic and optical properties. 32-34 With a judicious optimization of growth conditions, single NWs with a pure zinc-blende or wurzite structure can be obtained. [35][36][37] Still, the optical and electronic properties tend to fluctuate considerably from NW to NW, 2 which precludes the proper control of the response of an ensemble of nanowires.Recently, alternative approaches to obtain defect-free nano structures have been proposed. Particularly promising is the inversion of polarity from B to A...

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“…1 we show the PL spectum of sample E5/92 studied under the above-band-gap AlGaAs excitation. The PL spectrum observed consists of the AlGaAs donor-acceptor pair (DAP) emission at 6920 nm (1.791 eV) [4] and GaAs emissions with CAS related DAP PL at 1.493 eV [5], MnGa-related DAP PL at 1.403 eV [6] and an unidentified deep DAP PL at about 1 eV. It is interesting to notice that the 1.791 eV PL fits to DAP emission of AlGaAs with Al mole fraction of about 0.2 and is due to the Te donor-C acceptor transition [4].…”

Section: Resultsmentioning

confidence: 99%

AlGaAs to GaAs Energy Transfer Mechanisms in AlGaAs/GaAs Structures

et al. 1992

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New photoluminescence effects of carrier confinement at an AlGaAs/GaAs heterojunction interface

Cited by 96 publications

References 14 publications

Photoluminescence and the gallium problem for highest-mobility GaAs/AlGaAs-based 2d electron gases

Photoluminescence and the gallium problem for highest-mobility GaAs/AlGaAs-based 2d electron gases

Revealing Large-Scale Homogeneity and Trace Impurity Sensitivity of GaAs Nanoscale Membranes

AlGaAs to GaAs Energy Transfer Mechanisms in AlGaAs/GaAs Structures

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