Influence of surface passivation on the electrical properties of p–i–n GaAsP nanowires

Saket, Omar; Himwas, C.; Cattoni, Andréa; Oehler, Fabrice; Bayle, Fabien; Collin, Stéphane; Travers, Laurent; Babichev, A. V.; Julien, F. H.; Harmand, J. C.; Tchernycheva, Maria

doi:10.1063/5.0022157

Cited by 4 publications

(3 citation statements)

References 37 publications

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“…Owing to a large surface-to-volume ratio, high light absorption efficiency, considerable subwavelength size effect, and outstanding ability to separate and collect photoelectrons, one-dimensional semiconductor nanowires (NWs) are promoting the development of next-generation high-performance photodetectors. − However, with the large surface-to-volume ratio, the surface states caused by surface dangling bonds are abundant and important, contributing to Fermi level pinning and surface recombination. − Passivation is usually adopted to manipulate surface states to realize high-performance optoelectronic devices. − For example, Shen et al made use of aromatic thiolate-based molecular monolayers as a passivation layer to modify the surface states of InAs NWs, resulting in stable NW phototransistors with good sensitivity and fast photoresponse to low-intensity visible light . Interestingly, with passivation or not, a shell layer is generally observed on the surface of NWs, playing an unexpected important role in regulating the performance of NW photodetectors. − Under illumination, the observed shell layer has been considered as a photogating layer (PGL) in the literature to trap the photogenerated electrons and reduce the conductivity, bringing about the useful negative photoconductivity (NPC) effect. − For example, Guo et al and Fang et al find that the NPC effect caused by the surface shell can be used to reduce the dark current and enhance the infrared photodetection of single InAs NW photodetectors by a visible light-assisted method. , However, the shell layer originating from oxide or passivation is usually random and uncontrollable, − and hence, much effort should be focused on the scientific design and precise growth of the NPC-effect-caused shell during the NW growth process.…”

mentioning

confidence: 99%

In Situ Growth of GeS Nanowires with Sulfur-Rich Shell for Featured Negative Photoconductivity

Zhao

Sun

Yin

et al. 2021

J. Phys. Chem. Lett.

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The negative photoconductivity (NPC) effect originating from the surface shell layer has been considered as an efficient approach to improve the performance of optoelectronic nanodevices. However, a scientific design and precise growth of NPC-effect-caused shell during nanowire (NW) growth process for achieving high-performance photodetectors are still lacking. In this work, GeS NWs with a controlled sulfur-rich shell, diameter, and length are successfully prepared by a simple chemical vapor deposition method. As checked by transmission electron microscopy, the thickness of the sulfur-rich shell ranges from 10.5 ± 1.5 to 13.4 ± 2.5 nm by controlling the NW growth time. The composition of the sulfur-rich shell is studied by X-ray photoelectron spectroscopy, showing the decrease of S in the GeS x shell from the surface to core. When configured into the well-known phototransistor, a featured NPC effect is observed, benefiting the high-performance photodetector with high responsivity of 105 A·W–1 and detectivity of 1012 Jones for λ = 405 nm with ultralow intensity of 0.04 mW·cm–2. However, the thicker-shell NW phototransistor shows an unstable photodetector behavior with smaller negative photocurrent because of more hole-trapping states in the thicker shell. All results suggest a careful design and controlled growth of an NPC-effect-caused shell for future optoelectronic applications.

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mentioning

confidence: 99%

In Situ Growth of GeS Nanowires with Sulfur-Rich Shell for Featured Negative Photoconductivity

Zhao

Sun

Yin

et al. 2021

J. Phys. Chem. Lett.

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“…This approximation is valid if the electron beam is very far from the p-n junction and the diffusion length of charge carriers is very large compared to the average size of the generation volume. For devices with a significant surface to volume ratio (i.e., NWs), the effects due to surface recombination could dominate their characteristics [14,15]. In general, the v r value is an important parameter that affects the dark saturation current and the quantum efficiency of solar cells.…”

Section: Introductionmentioning

confidence: 99%

Modeling of the electron beam induced current signal in nanowires with an axial p-n junction

Lahreche¹,

Babichev²,

Beggah³

et al. 2022

Nanotechnology

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A tridimensional mathematical model to calculate the electron beam induced current (EBIC) of an axial p-n nanowire junction is proposed. The effect of the electron beam and junction parameters on the distribution of charge carriers and on the collected EBIC current is reported. We demonstrate that the diffusion of charge carriers within the wire is strongly influenced by the electrical state of its lateral surface which is characterized by a parameter called surface recombination velocity (v r). When the surface recombination is weak (i.e. low v r value), the diffusion of charge carriers occurs in one dimension (1-D) along the wire axis, and, in this case, the use of bulk EBIC models to extract the diffusion length (L) of charge carriers is justified. However, when the surface effects are strong (i.e. high v r values), the diffusion happens in three dimensions (3-D). In this case, the EBIC profiles depend on v r value and two distinct cases can be defined. If the L is larger than the nanowire radius (r a), the EBIC profiles show a strong dependency with this parameter. This gives evidence that the recombination of generated carriers on the surface through v r is the dominant process. In this situation, a decrease of two orders of magnitude in the EBIC profiles computed with a high and a low v r value is observed in neutral regions of the junction. For the case of L smaller than r a the dependency of the EBIC profiles on the v r is weak, and the prevalent recombination mechanism is the bulk recombination process.

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“…Electron beam induced current (EBIC) measurements have been proven to be a successful tool to investigate p-n junctions of both single NWs [17,[19][20][21][22], and processed NW solar cells [23][24][25]. Using this technique, single NWs are contacted in a scanning electron microscope (SEM) equipped with a piezocontrolled tungsten probe, enabling to measure EBIC and IV-characteristics.…”

Section: Introductionmentioning

confidence: 99%

Imaging the influence of oxides on the electrostatic potential of photovoltaic InP nanowires

et al. 2021

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Nanowires require surface passivation due to their inherent large surface to volume ratio. We investigate the effect of embedding InP nanowires in different oxides with respect to surface passivation by use of electron beam induced current measurements enabled by a nanoprobe based system inside a scanning electron microscope. The measurements reveal remote doping due to fixed charge carriers in the passivating POx/Al2O3 shell in contrast to results using SiOx. We used time-resolved photoluminescence to characterize the lifetime of charge carriers to evaluate the success of surface passivation. In addition, spatially resolved internal quantum efficiency simulations support and correlate the two applied techniques. We find that atomic-layer deposited POx/Al2O3 has the potential to passivate the surface of InP nanowires, but at the cost of inducing a field-effect on the nanowires, altering their electrostatic potential profile. The results show the importance of using complementary techniques to correctly evaluate and interpret processing related effects for optimization of nanowire-based optoelectronic devices.

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Influence of surface passivation on the electrical properties of p–i–n GaAsP nanowires

Cited by 4 publications

References 37 publications

In Situ Growth of GeS Nanowires with Sulfur-Rich Shell for Featured Negative Photoconductivity

In Situ Growth of GeS Nanowires with Sulfur-Rich Shell for Featured Negative Photoconductivity

Modeling of the electron beam induced current signal in nanowires with an axial p-n junction

Imaging the influence of oxides on the electrostatic potential of photovoltaic InP nanowires

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