Enhanced charge recombination due to surfaces and twin defects in GaAs nanostructures

Brown, Evan C.; Sheng, Chunyang; Shimamura, Kohei; Shimojo, Fuyuki; Nakano, Aiichiro

doi:10.1063/1.4907534

Cited by 18 publications

(19 citation statements)

References 53 publications

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“…Compared with thin film-based photodetectors, GaAs NWs-based photodetectors provide higher light sensitivity and internal photoconductivity gain because of their large surface-to-volume ratio and low area fill factor [14,15]. However, reports on the photoconductance properties of GaAs NWs are still lacking, most likely due to the large density of surface states, which tends to degrade device characteristics by pinning the surface Fermi energy [17][18][19][20]. Usually, an AlGaAs shell layer has been grown on the surface of the GaAs NWs to passivate the core surface effectively [14,16,21,22].…”

Section: Introductionmentioning

confidence: 98%

Self-catalyzed molecular beam epitaxy growth and their optoelectronic properties of vertical GaAs nanowires on Si(111)

Zhang

Geng

Zha

et al. 2016

Materials Science in Semiconductor Processing

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Section: Introductionmentioning

confidence: 98%

Self-catalyzed molecular beam epitaxy growth and their optoelectronic properties of vertical GaAs nanowires on Si(111)

Zhang

Geng

Zha

et al. 2016

Materials Science in Semiconductor Processing

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“…some excitons 22 and reduce charge carrier mobilities 23 . It has been proposed that they are responsible for enhanced recombination at the NW surfaces 24 , although surface recombination is a well-known problem that is addressed by core-shell structures to confine carriers to the NW core. 17…”

mentioning

confidence: 99%

Nonradiative Step Facets in Semiconductor Nanowires

Sanchez

Zhang

Tait³

et al. 2017

Nano Lett.

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One of the main advantages of nanowires for functional applications is their high perfection, which results from surface image forces that act on line defects such as dislocations, rendering them unstable and driving them out of the crystal. Here we show that there is a class of step facets that are stable in nanowires, with no long-range strain field or dislocation character. In zinc-blende semiconductors, they take the form of Σ3 (112) facets with heights constrained to be a multiple of three {111} monolayers. Density functional theory calculations show that they act as nonradiative recombination centers and have deleterious effects on nanowire properties. We present experimental observations of these defects on twin boundaries and twins that terminate inside GaAsP nanowires and find that they are indeed always multiples of three monolayers in height. Strategies to use the three-monolayer rule during growth to prevent their formation are discussed.

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“…Additionally, the presence of twin domains in tetragonal MAPbI 3 was discussed by Rothmann et al and is shown in figure 4(f) [84]. Twin boundaries impact charge separation, transport, and recombination [96]. The width of the twin domains present in MAPbI 3 films range from 100 to 300 nm and their formation/disappearance is reversible when transitioning through the cubic/tetragonal phase change [84].…”

Section: Nanoscale Absorber Level Characterizationmentioning

confidence: 85%

“…At the same time, a key goal is to characterize how perovskites transform in the presence of electric fields and illumination. Thus, in situ tracking of the evolution of perovskites in active devices represents a challenge but has been demonstrated recently employing interdigitated back-contacted substrates [96].…”

Section: Discussion and Outlookmentioning

confidence: 99%

Understanding macroscale functionality of metal halide perovskites in terms of nanoscale heterogeneities

2018

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Hybrid metal halide perovskites have shown an unprecedented rise as semiconductor building blocks for solar energy conversion and light-emitting applications. Currently, the field moves empirically towards more and more complex chemical compositions, including mixed halide quadruple cation compounds that allow optical properties to be tuned and show promise for better stability. Despite tremendous progress in the field, there is a need for better understanding of mechanisms of efficiency loss and instabilities to facilitate rational optimization of composition. Starting from the device level and then diving into nanoscale properties, we highlight how structural and compositional heterogeneities affect macroscopic optoelectronic characteristics. Furthermore, we provide an overview of some of the advanced spectroscopy and imaging methods that are used to probe disorder and non-uniformities. A unique feature of hybrid halide perovskite compounds is the propensity for these heterogeneities to evolve in space and time under relatively mild illumination and applied electric fields, such as those found within active devices. This introduces an additional challenge for characterization and calls for application of complimentary probes that can aid in correlating the properties of local disorder with macroscopic function, with the ultimate goal of rationally tailoring synthesis towards optimal structures and compositions.Organic-inorganic metal halide perovskites have attracted tremendous research attention as a fascinating class of semiconductors with applications in low-cost, high performance optoelectronics, including photovoltaics [1, 2], light emitting diodes [3], and lasers [4]. In particular, their exceptional photophysical properties, such as high defect tolerance compared to conventional semiconductors [5][6][7][8], long diffusion lengths [9], and long lifetimes [10], have motivated studies that attempt to elucidate the physical properties and interactions underlying desirable charge transport mechanisms and dynamics. Although extraordinarily high power conversion efficiencies have been achieved within about 10 years of research, there is a need to better understand mechanisms of efficiency loss and instabilities to facilitate rational optimization of composition. Currently, the field is driven empirically, going from the archetype CH 3 NH 3 PbI 3 to more and more complex chemical compositions, such as KCsFAMAPbI 3-x Br x (FA=CH(NH 2 ) 2 + , MA=CH 3 NH 3 + ), that allow precise tuning of the optical properties, stabilization of desired phases, and mitigation of photoinduced ion migration [11].Recent studies have revealed that there can be substantial heterogeneities in polycrystalline metal halide perovskite films [12][13][14][15][16][17][18]. These heterogeneities manifest on a variety of different length scales and can significantly influence the underlying structural, transport, and optoelectronic properties. The complex nature of metal halide perovskites has lately evoked the question of 'whether their ex...

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Enhanced charge recombination due to surfaces and twin defects in GaAs nanostructures

Cited by 18 publications

References 53 publications

Self-catalyzed molecular beam epitaxy growth and their optoelectronic properties of vertical GaAs nanowires on Si(111)

Self-catalyzed molecular beam epitaxy growth and their optoelectronic properties of vertical GaAs nanowires on Si(111)

Nonradiative Step Facets in Semiconductor Nanowires

Understanding macroscale functionality of metal halide perovskites in terms of nanoscale heterogeneities

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