Effects of Surface Passivation on Twin-Free GaAs Nanosheets

Arab, Shermin; Chi, Chau‐Hwa; Shi, Teng; Wang, Yuda; Dapkus, Daniel; Jackson, Howard E.; Smith, L. M.; Cronin, Stephen B.

doi:10.1021/nn505227q

Cited by 19 publications

(21 citation statements)

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“…Nanoscale membranes show relatively long minority carrier diffusion length of 180 nm at 4.2 K, which is significantly larger than the diffusion lengths found in nanowires. 40,41 Moreover, by introducing passivation and/or doped structures, the design can be further sophisticated. 40,41 The transfer of NW optoelectronic devices to industry requires achieving highly reproducible and uniform structures through a large surface area, so that the properties of ensemble and single object are indistinguishable.…”

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“…40,41 Moreover, by introducing passivation and/or doped structures, the design can be further sophisticated. 40,41 The transfer of NW optoelectronic devices to industry requires achieving highly reproducible and uniform structures through a large surface area, so that the properties of ensemble and single object are indistinguishable. For instance, in photoluminescence this implies indistinguishability in terms of line width and emission energy and spectral shape.…”

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confidence: 99%

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

et al. 2017

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“…Полупроводниковыми наноструктурами считаются структуры, размеры которых в одном или нескольких измерениях не превышают 100 нм. В частности, к ним относятся так называемые нанолисты [279], нанопроволоки [280,281] и нанокристаллы (квантовые точки) [282] (рис. 18).…”

Section: модификация характеристик полупроводниковых приборных структunclassified

Модификация Атомной И Электронной Структуры Поверхности Полупроводников А-=sup=-Iii-=/Sup=-В-=sup=-v-=/Sup=- На Границе С Растворами Электролитов О Б З Ор

Лебедев¹

2020

Физика И Техника Полупроводников

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Recent experimental and theoretical results on modification of the surface atomic and electronic structure of various III–V semiconductor with electrolyte solutions are reviewed. The relationship between the chemical and charge transfer processes that proceed at the semiconductor/electrolyte interfaces and accompanying modification of the semiconductor surface atomic and electronic structure is revealed. Advances in the application of electrolyte solutions for modification of the semiconductor nanostructures and device performance are discussed.

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“…1,2 Mechanisms of enhancement include increased density of electronic states in low dimensions, 3 increased phonon scattering, 4 and quantum confinement-induced band gap engineering. 5 However, in practice, reducing materials and devices to low dimensions (or nanoscale dimensions) often presents deleterious effects associated with poor electrical contacts, 6 surface depletion, 7,8 and unintentional doping, 9 which are not important in bulk material systems. For example, the thermoelectric performance of monolayer MoS 2 varies more widely than bulk MoS 2 .…”

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Enhanced thermoelectric efficiency in topological insulator Bi2Te3 nanoplates via atomic layer deposition-based surface passivation

Chen

Kim

Poudel

et al. 2018

Applied Physics Letters

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We report in-plane thermoelectric measurements of Bi 2 Te 3 nanoplates, a typical topological insulator with Dirac-like metallic surface states, grown by chemical vapor deposition. The as-grown flakes exposed to ambient conditions exhibit relatively small thermopowers around À34 lV/K due to unintentional surface doping (e.g., gas adsorption and surface oxidation). After removal of the unintentional surface doping and surface passivation by deposition of 30 nm of Al 2 O 3 using atomic layer deposition (ALD), the Seebeck coefficient of these flakes increases by a factor of 5Â to À169 lV/K. Here, we believe that the ALD-based surface passivation can prevent the degradation of the thermoelectric properties caused by gas adsorption and surface oxidation processes, thus, reducing the unintentional doping in the Bi 2 Te 3 and increasing the Seebeck coefficient. The high surface-to-volume ratio of these thin ($10 nm thick) nanoplates make them especially sensitive to surface doping, which is a common problem among nanomaterials in general. An increase in the sample resistance is also observed after the ALD process, which is consistent with the decrease in doping.

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Effects of Surface Passivation on Twin-Free GaAs Nanosheets

Cited by 19 publications

References 24 publications

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

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

Модификация Атомной И Электронной Структуры Поверхности Полупроводников А-=sup=-Iii-=/Sup=-В-=sup=-v-=/Sup=- На Границе С Растворами Электролитов О Б З Ор

Enhanced thermoelectric efficiency in topological insulator Bi2Te3 nanoplates via atomic layer deposition-based surface passivation

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