Unravelling the strain relaxation processes in silicon nanowire arrays by X-ray diffraction

Romanițan, Cosmin; Kusko, Mihaela; Popescu, Marian; Varasteanu, Pericle; Radoi, Antonio; Pachiu, Cristina

doi:10.1107/s1600576719010707

Cited by 12 publications

(8 citation statements)

References 65 publications

(61 reference statements)

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“…10 (a). Similarly, the pristine NWs exhibit higher strain 42 , and upon sintering, surface energy minimization stabilizes the lattice vibration and reduces stress and strain on the NWs array, as confirmed from Fig. 10 (b).…”

Section: Discussionmentioning

confidence: 59%

Removal of Ag remanence and improvement in structural attributes of silicon nanowires array via sintering

Kale

Sahoo

2021

Sci Rep

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Metal-assisted chemical etching (MACE) is popular due to the large-area fabrication of silicon nanowires (SiNWs) exhibiting a high aspect ratio at a low cost. The remanence of metal, i.e., silver nanoparticles (AgNPs) used in the MACE, deteriorates the device (especially solar cell) performance by acting as a defect center. The superhydrophobic behavior of nanowires (NWs) array prohibits any liquid-based solution (i.e., thorough cleaning with HNO3 solution) from removing the AgNPs. Thermal treatment of NWs is an alternative approach to reduce the Ag remanence. Sintering temperature variation is chosen between the melting temperature of bulk-Ag (962 °C) and bulk-Si (1412 °C) to reduce the Ag particles and improve the crystallinity of the NWs. The melting point of NWs decreases due to surface melting that restricts the sintering temperature to 1200 °C. The minimum sintering temperature is set to 1000 °C to eradicate the Ag remanence. The SEM–EDS analysis is carried out to quantify the reduction in Ag remanence in the sintered NWs array. The XRD analysis is performed to study the oxides (SiO and Ag2O) formed in the NWs array due to the trace oxygen level in the furnace. The TG-DSC characterization is carried out to know the critical sintering temperature at which remanence of AgNPs removes without forming any oxides. The Raman analysis is studied to determine the crystallinity, strain, and size of Si nanocrystals (SiNCs) formed on the NWs surface due to sidewalls etching. An optimized polynomial equation is derived to find the SiNCs size for various sintering temperatures.

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Section: Discussionmentioning

confidence: 59%

Removal of Ag remanence and improvement in structural attributes of silicon nanowires array via sintering

Kale

Sahoo

2021

Sci Rep

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“…4(e) and 4( f)]. In contrast to Si nanowires, for which we showed that the bending and torsion phenomena govern the strain formation and the coalescence joints favor the strain relaxation processes (Romanitan et al, 2019), these measurements show no evidence of strain relaxation (i.e. relaxation degree is zero) in porous layers.…”

Section: Research Papersmentioning

confidence: 67%

X-ray scattering profiles: revealing the porosity gradient in porous silicon

et al. 2021

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Porous silicon layers with different porosities were prepared by adjusting the anodization current density of the electrochemical etching process, starting from highly doped p-type crystalline silicon wafers. The microstructural parameters of the porous layers were assessed by high-resolution X-ray diffraction, total external reflection, scanning electron microscopy and nitrogen adsorption–desorption analysis. Furthermore, both the surface porosity and the mean porosity for the entire volume of the samples were estimated by employing total external reflection measurements and X-ray reciprocal-space mapping, respectively. The results clearly indicate that the surface porosity is different from the mean porosity, and the presence of a depth porosity gradient is suggested. To evaluate the porosity gradient in a nondestructive way, a new laboratory method using the grazing-incidence X-ray diffraction technique is reported. It is based on the analysis of the X-ray scattering profiles of the porous layers to obtain the static Debye–Waller factors. In this way, a description of the porosity gradient in a quantitative framework becomes possible, and, as a result, it was shown that the porosity increases exponentially with the X-ray penetration depth. Moreover, a strong dependence between the porosity gradient and the anodization current was demonstrated. Thus, in the case of the lowest anodization current (e.g. 50 mA cm−2) a variation of only 15% of the porosity from the surface to the interface is found, but when applying a high anodization current of 110 mA cm−2 the porosity close to the bulk interface is almost three times higher than at the surface.

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“…This is possible by taking into account the small length of our arrays. Also, previous investigations in highly dense nanowire arrays prepared by MACE showed the occurrence of edge and screw threading dislocations only for wires longer than 9 µm [23]. At the same time, we must consider the previous findings from the rocking curves profiles, indicating a relationship between the array length and the XRDS intensity, which was attributed to the presence of the structural defects.…”

Section: A Structure and Pl Properties Of Silicon Nanowiresmentioning

confidence: 82%

“…These profiles were obtained in the framework of grazing-incidence X-ray diffraction on highlyasymmetric (111) reflection, which allowed us to attain different X-ray penetration depths, varying the incidence angles of the X-ray source. Further details regarding the grazingincidence X-ray diffraction technique on (111) in nanowires, as well as for the bending profiles can be found in [23].…”

Section: A Structure and Pl Properties Of Silicon Nanowiresmentioning

confidence: 99%