Dislocations in laser-doped silicon detected by micro-photoluminescence spectroscopy

Nguyen, Hieu T.; Han, Young Joon; Fell, Andreas; Franklin, Evan; Macdonald, Daniel

doi:10.1063/1.4926360

Cited by 29 publications

(22 citation statements)

References 30 publications

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“…This similar feature has been reported in laser-annealed silicon, which show a multitude of broad bands at around 1360 nm [30], whereas distinctive D1-D4 lines are observed by other authors [31]. Moreover, a specific luminescent peak at around 1270 nm, showing similar features compared to dislocation-related luminescent peaks at a sub-grain boundary of a mc-Si, is also observed near the edge of laser-doped regions [11]. Compared to the PL spectra in Figs.…”

Section: Pl Spectra Of Excimer Laser Boron-doped Silicon Substratessupporting

confidence: 68%

“…2, 3 shows elevated PL signal in this range without specific dislocation peaks being evident. In fact, dislocation peaks such as D3 and D4 lines may still be present, but might be masked by the PL signal of continuous deep levels formed by the laser doping process [11]. It is additionally possible that the density of intrinsic dislocations (D3 and D4) might actually be suppressed due to the dislocation pinning effect of boron dopants in the laser-doped region, as reported previously for heavily doped silicon [32,33].…”

Section: Pl Spectra Of Excimer Laser Boron-doped Silicon Substratesmentioning

confidence: 90%

“…However, laser doping has been known to induce defects or dislocations in silicon [10][11][12]. Moreover, characterization of laser-doped regions is quite challenging using conventional characterization methods due to the micron-scale features typically produced via laser processing.…”

Section: Introductionmentioning

confidence: 99%

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Low-temperature micro-photoluminescence spectroscopy on laser-doped silicon with different surface conditions

et al. 2016

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Low-temperature micro-photoluminescence spectroscopy (μ-PLS) is applied to investigate shallow layers of laser-processed silicon for solar cell applications. Micron-scale measurement (with spatial resolution down to 1 μm) enables investigation of the fundamental impact of laser processing on the electronic properties of silicon as a function of position within the laser-processed region, and in particular at specific positions such as at the boundary/ edge of processed and unprocessed regions. Low-temperature μ-PLS enables qualitative analysis of laser-processed regions by identifying PLS signals corresponding to both laser-induced doping and laser-induced damage. We show that the position of particular luminescence peaks can be attributed to band-gap narrowing corresponding to different levels of subsurface laser doping, which is achieved via multiple 248 nm nanosecond excimer laser pulses with fluences in the range 1.5-4 J/cm 2 and using commercially available boron-rich spin-on-dopant precursor films. We demonstrate that characteristic defect PL spectra can be observed subsequent to laser doping, providing evidence of laser-induced crystal damage. The impact of laser parameters such as fluence and number of repeat pulses on laserinduced damage is also analyzed by observing the relative level of defect PL spectra and absolute luminescence intensity. Luminescence owing to laser-induced damage is observed to be considerably larger at the boundaries of laser-doped regions than at the centers, highlighting the significant role of the edges of laser-doped region on laser doping quality. Furthermore, by comparing the damage signal observed after laser processing of two different substrate surface conditions (chemically-mechanically polished and tetramethylammonium hydroxide etched), we show that wafer preparation can be an important factor impacting the quality of laser-processed silicon and solar cells.

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Section: Pl Spectra Of Excimer Laser Boron-doped Silicon Substratessupporting

confidence: 68%

Section: Pl Spectra Of Excimer Laser Boron-doped Silicon Substratesmentioning

confidence: 90%

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Low-temperature micro-photoluminescence spectroscopy on laser-doped silicon with different surface conditions

et al. 2016

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“…This fact has been demonstrated by the detection of dislocations [7] and certain levels of mechanical stress [8], [9] in the regions processed by laser. In addition to these micro-structural studies, other analysis such as the study of the composition [10], the estimation of the doping level [8], [9], and the study of the electronic properties [11], [12] of LPRs have been also carried out in the last years.…”

Section: Introductionmentioning

confidence: 98%

Microscale Characterization of Surface Recombination at the Vicinity of Laser-Processed Regions in c-Si Solar Cells

Roigé

Ossó

Martı́n

et al. 2016

IEEE J. Photovoltaics

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Laser firing processes have emerged as a technologically feasible approach to fabricate local point contacts or local doped regions in advanced high-efficiency crystalline-Si (c-Si) solar cells. In this work we analyze the local impact induced by the laser pulse on the passivation layers, which are commonly present in advanced c-Si solar cell architectures to reduce surface recombination. We use micro-photoluminescence (PL) measurements with a spatial resolution of 7 µm to evaluate the passivation performance at the surroundings of laser processed regions (LPRs). In particular, we have studied LPRs performed on SiCx/Al2O3-and Al2O3-passivated c-Si wafers by an IR (1064 nm) laser. Micro-PL results show that passivation quality of c-Si surface is affected up to about 100 µm away from the LPR border, and that the extension of this damaged zone is correlated to the laser power and to the presence of capping layers. In the final part of the work, the observed decrease in passivation quality is included into an improved 3D simulation model that gives accurate information about the recombination velocities associated to the studied LPRs.

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“…8 Confocal micro-PL spectroscopy has become during the last few years an important experimental tool for developing novel and comprehensive studies of advanced solar cell concepts 9 with micron resolution. In particular, micro-PL measurements have been extensively used to perform highresolution spatially resolved studies of different properties and material features, including the analysis of microstructural defects, 10 the estimation of doping densities, 11,12 and the detection of precipitates and impurities. 13 In confocal micro-PL measurements, a laser light is focused onto the surface of the sample to be studied by microscope objectives, and the backscattered PL signal is collected via a confocal aperture.…”

Section: Introductionmentioning

confidence: 99%

Effects of photon reabsorption phenomena in confocal micro-photoluminescence measurements in crystalline silicon

Roigé

Alvarez

Jaffré

et al. 2017

Journal of Applied Physics

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Confocal micro-photoluminescence (PL) spectroscopy has become a powerful characterization technique for studying novel photovoltaic (PV) materials and structures at the micrometer level. In this work, we present a comprehensive study about the effects and implications of photon reabsorption phenomena on confocal micro-PL measurements in crystalline silicon (c-Si), the workhorse material of the PV industry. First, supported by theoretical calculations, we show that the level of reabsorption is intrinsically linked to the selected experimental parameters, i.e., focusing lens, pinhole aperture, and excitation wavelength, as they define the spatial extension of the confocal detection volume, and therefore, the effective photon traveling distance before collection. Second, we also show that certain sample properties such as the reflectance and/or the surface recombination velocity can also have a relevant impact on reabsorption. Due to the direct relationship between the reabsorption level and the spectral line shape of the resulting PL emission signal, reabsorption phenomena play a paramount role in certain types of micro-PL measurements. This is demonstrated by means of two practical and current examples studied using confocal PL, namely, the estimation of doping densities in c-Si and the study of back-surface and/or back-contacted Si devices such as interdigitated back contact solar cells, where reabsorption processes should be taken into account for the proper interpretation and quantification of the obtained PL data. Published by AIP Publishing.

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Dislocations in laser-doped silicon detected by micro-photoluminescence spectroscopy

Cited by 29 publications

References 30 publications

Low-temperature micro-photoluminescence spectroscopy on laser-doped silicon with different surface conditions

Low-temperature micro-photoluminescence spectroscopy on laser-doped silicon with different surface conditions

Microscale Characterization of Surface Recombination at the Vicinity of Laser-Processed Regions in c-Si Solar Cells

Effects of photon reabsorption phenomena in confocal micro-photoluminescence measurements in crystalline silicon

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