Mobility and carrier concentration in polycrystalline silicon

Joshi, D. P.; Srivastava, R. S.

doi:10.1016/0379-6787(84)90112-1

Cited by 16 publications

(7 citation statements)

References 15 publications

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“…Although N t can vary significantly depending on the grain size of the poly-Si, these numbers are on the order reported in the literature. [33][34][35][36]40,47 As expected, n eff drops more steeply as the net doping concentration approaches N t . In agreement with the resistor model described previously, n eff is roughly equal to the difference between net doping and N t .…”

Section: ■ Results and Discussionsupporting

confidence: 73%

“…For a set of n- and p-type dopant concentration profiles in the isolation region, Figure b shows n eff (dashed lines) for three values of N t 2.3 × 10 17 , 9 × 10 17 , and 2.3 × 10 18 cm –3 . Although N t can vary significantly depending on the grain size of the poly-Si, these numbers are on the order reported in the literature. − ,, As expected, n eff drops more steeply as the net doping concentration approaches N t . In agreement with the resistor model described previously, n eff is roughly equal to the difference between net doping and N t .…”

Section: Resultssupporting

confidence: 69%

“…To understand why SSRM shows a wide high resistivity region and why KPFM shows a gradual increase in potential, we account for the existence of trap states in poly-Si, which are most likely present in the grain boundaries. These trap states ,,, capture charge carriers, which creates a potential barrier for transport through the conduction or valence bands, causing a reduction of carrier mobility. , The reduction in carrier mobility is the highest when the Fermi energy of poly-Si is close to the energy levels of the trap state , and the net carrier concentration is approximately equal to N t . In addition to the reduction in mobility from potential barriers at grain boundaries, mobility is further lowered due to scattering of carriers off the ionized dopants within the poly-Si .…”

Section: Resultsmentioning

confidence: 99%

“…To account for trap states in poly-Si, we subtract the trap density, N t , from the net dopant concentration to determine the effective dopant concentration, n eff (see Figure b). The local resistivity in the p–i–n structure was obtained either from the literature ,, or estimated based on the carrier concentration and mobility in poly-Si. The resistivity was determined for different isolation region widths, δ, over the range of 20–55 μm ,, and for different characteristic diffusion lengths, L diff , over the range 50–100 μm (see Supporting Information).…”

Section: Experimental and Simulation Detailsmentioning

confidence: 99%

“…While the primary focus of this work is of poly-Si p–i–n structures across doped IBC fingers, this type of structure has been demonstrated for use in other semiconductor devices such as electro-optical devices and coplanar thin film diodes. − We consider the effect of compensation in this region leading to reduced conductivity due to reduced net free carrier concentration, n eff . Importantly, n eff will be significantly reduced by capture of carriers at grain boundary and bulk defects that are abound in poly-Si. − We call this trap-assisted compensation. With this mechanism, we determine the necessary conditions for characteristic diffusion length, finger separation, and trap defect density under which an appropriately resistive region will form.…”

Section: Introductionmentioning

confidence: 99%

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Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

Hartenstein

Stetson

Nemeth

et al. 2021

ACS Appl. Energy Mater.

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Using a trap-assisted compensation model, we explain why polycrystalline Si (poly-Si) passivating contacts are able to achieve low leakage current between the doped fingers of interdigitated back contact (IBC) monocrystalline Si solar cells despite mixing of boron and phosphorus dopants in the isolation region. The fill factor of IBC solar cells is strongly affected by the electrical isolation region between n- and p-type fingers, as this region is critical in minimizing shunting losses. During fabrication of monocrystalline Si solar cells with poly-Si passivating contacts, the intrinsic poly-Si isolation region inevitably gets contaminated with both p- and n-type dopants. Using dopant profiles measured with time-of-flight secondary ion mass spectrometry and scanning probe measurements of the isolation region, we demonstrate that despite the dopant spreading during cell processing, a well-compensated region between the doped fingers exists that prevents shunting. The trap-assisted dopant compensation mechanism significantly widens the compensated region to tens of microns, where the residual dopant densities are below the trap density. This enables a high-resistivity region, resulting in low shunt current. Using one-dimensional (1-D) finite element diode simulations, we identify the design parameters and experimental conditions under which a sufficiently resistive region can form. Our measurements of 2-D local resistivity and work function maps across the isolation region using scanning spreading resistance microscopy and Kelvin probe force microscopy demonstrate the existence of a highly resistive, wide compensated region and confirm our proposed compensation mechanism. For our structures, this region is ∼25 μm in width within a ∼150 μm wide finger isolation region with nearly 3 orders of magnitude higher resistivity than the regions dominated by a single type of dopant.

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Section: ■ Results and Discussionsupporting

confidence: 73%

Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Section: Experimental and Simulation Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

Hartenstein

Stetson

Nemeth

et al. 2021

ACS Appl. Energy Mater.

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Large Polaron Conduction, Photoconductivity, and Photochromism in GdO_xH₃_−2x Oxyhydride Thin Films

Colombi

Boshuizen

Chaykina

et al. 2023

Advanced Optical Materials

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At ambient conditions, rare‐earth oxyhydride thin films show reversible photochromism and photoconductivity, while their mechanism and relation are still unclear. In this work, this question is explored with in situ time‐resolved measurements of both optical and transport properties of Gd‐based oxyhydride thin films. It is found that p‐type large polaron conduction is the initial mechanism of charge transport; however, upon photo‐darkening, a 104‐fold increase of conductivity occurs, and n‐type carriers become dominant. Further, photochromism and photoconductivity are shown to originate from a single process, as indicated by the fact that the photoconductivity is exponentially proportional to the increase of optical absorption. This exponential relation, notably, cannot stem from any of the optically absorbing species thought responsible for photochromism and, therefore, suggests that their formation is accompanied by a concerted increase of negative charge carriers in the Gd oxyhydride films.

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Carrier recombination at grain boundaries in polycrystalline silicon under optical illumination

Joshi¹

1986

Solid-State Electronics

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Mobility and carrier concentration in polycrystalline silicon

Cited by 16 publications

References 15 publications

Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

Large Polaron Conduction, Photoconductivity, and Photochromism in GdO_xH₃_−2x Oxyhydride Thin Films

Carrier recombination at grain boundaries in polycrystalline silicon under optical illumination

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Mobility and carrier concentration in polycrystalline silicon

Cited by 16 publications

References 15 publications

Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

Large Polaron Conduction, Photoconductivity, and Photochromism in GdOxH3−2x Oxyhydride Thin Films

Carrier recombination at grain boundaries in polycrystalline silicon under optical illumination

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Large Polaron Conduction, Photoconductivity, and Photochromism in GdO_xH₃_−2x Oxyhydride Thin Films