Recrystallization of Polycrystalline CVD Grown Silicon

Schins, W. J. H.; Bezemer, Jeff; Holtrop, H.; Radelaar, S.

doi:10.1149/1.2129846

Cited by 29 publications

(7 citation statements)

References 5 publications

(6 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, in previous studies the primary <110> fiber texture of the as-grown materials was converted into a strong <111> texture with free rotation around this axis after recrystallization. [30,33] In comparison, despite the existence of some abnormal elongated grains with length of %30 μm coinciding with the original grain growth direction in the recrystallization microstructure in the present study, we found no preferred <111> texture in the matrix by EBSD analysis. This can be possibly attributed to different grain growth profiles of the starting materials, leading to different numbers of grown-in crystal defects which provide different levels of driving force upon high temperature annealing.…”

Section: Evolution Of Microstructure With Processingcontrasting

confidence: 76%

“…Our characterization results for as-received polycrystalline silicon are broadly consistent with those from other studies. [12,30,31] In previous reports, the <110> preferred growth orientation was not only observed in bulk CVD polycrystalline silicon, [30] but also in polysilicon films produced by the CVD method on different silicon substrates. [32] It was suggested that the high surface energy of the (110) planes causes the crystallites to grow in the <110> direction, that is, nucleation of {110} islands is kinetically favored.…”

Section: Comparison Of Hr-ebsd Gnd Densities With Preferential Etchingmentioning

confidence: 89%

“…[32] It was suggested that the high surface energy of the (110) planes causes the crystallites to grow in the <110> direction, that is, nucleation of {110} islands is kinetically favored. [32] However, the surface microstructure of polycrystalline silicon in previous studies [12,[30][31][32] was only examined qualitatively by optical metallography and the existence of growth twins was only inferred from the appearance of striated needle clusters. Our study provides a more direct characterization of the defect morphology and crystallography.…”

Section: Comparison Of Hr-ebsd Gnd Densities With Preferential Etchingmentioning

confidence: 99%

“…The recrystallization behavior of as-received polysilicon is consistent with previous studies but with a significantly shorter period of time. [12,30,33] Schins et al [30] found that fine grained (0.1-10 μm) high purity bulk polycrystalline silicon grown by CVD can be recrystallized to larger oblong grains (20-2 mm in length and 20-100 μm in diameter) by 3 h thermal treatment at elevated temperatures between 1350 and 1400 C. Their starting material and annealing conditions are relatively similar to ours, but we find a much shorter time for nearly complete recrystallization and more homogeneous microstructure with equiaxed grains in smaller average size (%30 μm in diameter). In addition, in previous studies the primary <110> fiber texture of the as-grown materials was converted into a strong <111> texture with free rotation around this axis after recrystallization.…”

Section: Evolution Of Microstructure With Processingmentioning

confidence: 99%

See 3 more Smart Citations

Microstructural Evolution of Mechanically Deformed Polycrystalline Silicon for Kerfless Photovoltaics

Murphy

Jiang

et al. 2018

Physica Status Solidi (a)

View full text Add to dashboard Cite

Silicon wafers for photovoltaics could be produced without kerf loss by rolling, provided sufficient control of defects such as dislocations can be achieved. A study using mainly high resolution electron backscatter diffraction (HR‐EBSD) of the microstructural evolution of Siemens polycrystalline silicon feedstock during a series of processes designed to mimic high temperature rolling is reported here. The starting material is heavily textured and annealing at 1400 °C results in 90% recrystallization and a reduction in average geometrically necessary dislocation (GND) density from >1014 to 1013 m−2. Subsequent compression at 1150 °C – analogous to rolling – produce sub‐grain boundaries seen as continuous curved high GND content linear features spanning grain interiors. Post‐deformation annealing at 1400 °C facilitates a secondary recrystallization process, resulting in large grains typically of 100 μm diameter. HR‐EBSD gives the final average GND density in as 3.2 × 1012 m−2. This value is considerably higher than the dislocation density of 5 × 1010 m−2 from etch pit counting, so the discrepancy is investigated by direct comparison of GND maps and etch pit patterns. The GND map from HR‐EBSD gives erroneously high values at the method's noise floor (≈1012 m−2) in regions with low dislocation densities.

show abstract

Section: Evolution Of Microstructure With Processingcontrasting

confidence: 76%

Section: Comparison Of Hr-ebsd Gnd Densities With Preferential Etchingmentioning

confidence: 89%

Section: Comparison Of Hr-ebsd Gnd Densities With Preferential Etchingmentioning

confidence: 99%

Section: Evolution Of Microstructure With Processingmentioning

confidence: 99%

See 2 more Smart Citations

Microstructural Evolution of Mechanically Deformed Polycrystalline Silicon for Kerfless Photovoltaics

Murphy

Jiang

et al. 2018

Physica Status Solidi (a)

View full text Add to dashboard Cite

show abstract

“…These defects can be eliminated by heating above 750 °C . Recrystallization of grains, which is advantageous to further increase their size, does not happen appreciably at temperatures below 1000 °C and accelerates as the temperature increases above 1200 °C. , Fortunately, in contrast to most planar electronic devices, HPCVD-grown amorphous silicon optical fibers can withstand temperature as high as 1300 °C for ∼10 min without deformation of the silica cladding. Thus, it seems a two-step annealing process should be best for the formation of large grains in these fibers.…”

mentioning

confidence: 99%

Crystalline Silicon Optical Fibers with Low Optical Loss

Chaudhuri¹,

Sparks

Ji³

et al. 2016

ACS Photonics

View full text Add to dashboard Cite

Polycrystalline silicon core optical fibers have been fabricated by modified thermal annealing of amorphous silicon chemically deposited at high pressure. The resulting fibers have small-diameter cores, a geometry advantageous for optical guidance. Moreover, the combination of chemical deposition and annealing avoids difficulties associated with undesired transfer of oxygen impurities to the silicon core from the molten cladding during the drawing process. The high aspect ratio of the amorphous silicon core and the presence of the silica cladding surrounding make the design rules for annealing to optimize their polycrystalline structure different from those of conventional amorphous silicon films. We find that optimization of the annealing allows for an increase in the polycrystalline grain size and decrease in the defects in the silicon core. A low optical loss of less than 1 dB/cm at a wavelength of 2.2 μm is thus realized, much lower than that reported for small core size (<10 μm) crystalline silicon fibers and comparable to the loss in many planar semiconductor waveguides. This loss is just below the threshold of 1 dB/cm often considered necessary for many photonic and optoelectronic applications at near to mid-infrared wavelengths in areas such as nonlinear photonics, lasers, and in-fiber photodetectors. Further reduction in optical losses as deposition and annealing techniques are improved can be anticipated.

show abstract