Growth optimization and characterization of regular arrays of GaAs/AlGaAs core/shell nanowires for tandem solar cells on silicon

Vettori, Marco; Piazza, Valerio; Cattoni, Andréa; Scaccabarozzi, Andrea; Patriarche, G.; Régrény, Philippe; Chauvin, Nicolas; Botella, Claude; Grenet, Geneviève; Penuelas, Jose; Fave, Alain; Tchernycheva, Maria; Gendry, M.

doi:10.1088/1361-6528/aaf3fe

Cited by 21 publications

(26 citation statements)

References 65 publications

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“…Such a result is consistent with models previously developed by others 3,18,25,26,28,30 but it should be considered as specific for the diffusion of Ga adatoms on SiO 2 -terminated Si substrates, with a thin SiO 2 surface layer 1 − 2 nm-thick, where the Ga adatom diffusion length is longer, whereas Ga adatoms can behave differently on thicker SiO 2 masks (typically 10 − 20 nm-thick) used for substrate patterning, 18 as shown elsewhere. 23,32 It is interesting to notice that, in agreement with results in references, 7,30 both classes of NWs evolve toward a stationnary growth regime when the amount of As and Ga atoms are identical and the growth mode is only axial. This asymptotic behavior is determined by two main factors: the fact that the V/III flux ratio is greater than 1 and the existence of a diffusion length for Ga adatoms along the NW facets.…”

Section: 2supporting

confidence: 87%

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Impact of the Ga flux incidence angle on the growth kinetics of self-assisted GaAs nanowires on Si(111)

et al. 2019

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In this work we show that the incidence angle of group-III elements fluxes plays a significant role on the diffusion-controlled growth of III-V nanowires (NWs) by molecular beam epitaxy (MBE). We present a thorough experimental study on the self-assisted growth of GaAs NWs by using a MBE reactor equipped with two Ga cells located at different incidence angles with respect to the surface normal of the substrate, so as to ascertain the impact of such a parameter on the NW growth kinetics. The as-obtained results show a dramatic influence of the Ga flux incidence angle on the NW length and diameter, as well as on the shape and size of the Ga droplets acting as catalysts. In order to interpret the results we developed a semi-empirical analytic model inspired by those already developed for MBE-grown Au-catalyzed GaAs NWs. Numerical simulations performed with the model allow to reproduce thoroughly the experimental results (in terms of NW length and diameter and of droplet size and wetting angle), putting 1 arXiv:1907.03226v1 [cond-mat.mes-hall] 7 Jul 2019 in evidence that under formally the same experimental conditions the incidence angle of the Ga flux is a key parameter which can drastically affect the growth kinetics of the NWs grown by MBE. IntroductionGaAs nanowires (NWs) are one of the most promising materials for the integration of III-V semiconductors on Si, since they can be grown by molecular beam epitaxy (MBE) on Si substrates via self-assisted vapor-liquid-solid (VLS) mechanism 1-8 preventing the use of Au catalyst which would jeopardize the electronic and optoelectronic properties of these semiconductors, forming deep-level states in both of them. 9-14 When it comes to MBE, both Au-catalyzed and self-assisted growths of NWs are diffusion-controlled processes. Many theoretical and experimental studies were carried out to understand the growth mechanisms and to identify the parameters influencing the NW structure and the growth kinetics. 2,3,7,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] First works have shown that the catalyst droplet volume or shape 15,16,18,27,31 and, more recently, that the droplet wetting angle 20,22,24 do control the NW crystal structure through the location of the nucleation site. Moreover, the volume of the catalyst droplet controls the kinetics of the axial growth through the related capture surface, 25,26,28 and in particular, through the capture area for As in the case of self-assisted GaAs NWs. 18,22 Concerning the NW growth kinetics, the growth models developed so far take into account the Ga flux incidence angle 17,18,22,23,25,26,28,30 but do not demonstrate its influence. In particular, the model of Glas et al 17 for self-assisted GaAs NWs was based on the assumption that the Ga flux adopted is always high enough to supply the Ga droplet, therefore neglecting to consider the influence of the incidence angle of the Ga flux on the amount of

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Section: 2supporting

confidence: 87%

“…The growth conditions adopted (cf. -Experimental section) are the same as those one employed in ref., 32 which have proved to provide GaAs NWs with zinc-blende (ZB) structure. SEM images of as-obtained NWs (cf.…”

Section: Resultsmentioning

confidence: 99%

Impact of the Ga flux incidence angle on the growth kinetics of self-assisted GaAs nanowires on Si(111)

et al. 2019

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“…This seems contradictory with the results prviously presented as the droplet is expected to wet on the edge of the cavity: i.e., a part of the bottom and a part of the side. However, is also known that the cavities in the SiO 2 /Si substrate are not exactly cylindrical (see [12]). The process of creation of the cavities involves a treatment of the surface with fluorhydric acid to remove the remaining SiO 2 at the bottom of the cavities.…”

Section: Droplet In a Conical Cavitymentioning

confidence: 99%

Wetting of Ga droplets in SiO$_2$/Si cavities: Application to self-assisted GaAs nanowire growth

Bailly-Salins¹,

Vettori²,

Dursap³

et al. 2022

Preprint

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In this paper we compute and compare the surface energy of various Ga liquid droplets wetting a cylindrical cavity in various configurations. While for some of these configurations the surface energy can be computed explicitely for others numerical computation is needed. Motivated by the results obtained for the cylindrical cavities we explore the case of the more realistic situation, conical cavities. Our results provide a relation between the geometry of the conical cavity and the equilibirum wetting angles of the droplet on the bottom and on the sidewall of the cavity which insure the dewetting of the lateral surface. This is an important result toward the control of the verticality during the nanowire growth by the vapor liquid solid method.

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“…One way to tune the NW density is by substrate patterning followed by selective area growth (SAG) [9]. However, this method demands considerable efforts in terms of time, expertise and equipment.…”

Section: Introductionmentioning

confidence: 99%

Density-controlled growth of vertical InP nanowires on Si(111) substrates

Jaffal¹,

Régrény²,

Patriarche³

et al. 2020

Nanotechnology

Self Cite

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A procedure to achieve the density-controlled growth of gold-catalyzed InP nanowires (NWs) on (111) silicon substrates using the vapor-liquid-solid method by molecular beam epitaxy is reported. We develop an effective and mask-free method based on controlling the number and the size of the Au-In catalyst droplets in addition to the conditions for the NW nucleation. We show that the NW density can be tuned with values in the range of 18 µm -2 to < 0.1 µm -2 by the suitable choice of the In/Au catalyst beam equivalent pressure (BEP) ratio, by the phosphorous BEP and the growth temperature. The same degree of control is transferred to InAs/InP quantum dot-nanowires, taking advantage of the ultra-low density to study by micro-photoluminescence the optical properties of a single quantum dot-nanowires emitting in the telecom band monolithically grown on silicon. Optical spectroscopy at cryogenic temperature successfully confirmed the relevance of our method to excite single InAs quantum dots on the as-grown sample, which opens the path for large-scale applications based on single quantum dot-nanowire devices integrated on silicon.

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Growth optimization and characterization of regular arrays of GaAs/AlGaAs core/shell nanowires for tandem solar cells on silicon

Cited by 21 publications

References 65 publications

Impact of the Ga flux incidence angle on the growth kinetics of self-assisted GaAs nanowires on Si(111)

Impact of the Ga flux incidence angle on the growth kinetics of self-assisted GaAs nanowires on Si(111)

Wetting of Ga droplets in SiO$_2$/Si cavities: Application to self-assisted GaAs nanowire growth

Density-controlled growth of vertical InP nanowires on Si(111) substrates

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