Grain boundary diffusion of phosphorus in polycrystalline silicon
TL;DR: In this paper, an Arrhenius plot of grain boundary diffusion coefficients gave rise to an activation energy of 2.65 eV and preexponential factor D'0=4.8*10-3 cm2 s-1.
Abstract: Diffusion of radioactive phosphorus in polycrystalline silicon has been studied in the temperature range 566-980 degrees C. Diffusion profiles were obtained by anodic oxidation sectioning coupled with radio tracer detection. Diffusion coefficients in the grain boundary were obtained following Leclaire's method of analysis. An Arrhenius plot of grain boundary diffusion coefficients gave rise to an activation energy of 2.65 eV and pre-exponential factor D'0=4.8*10-3 cm2 s-1.
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TL;DR: In this paper, the dopant diffusion path in n-and p-types polycrystalline-Si gates of trench-type three-dimensional (3D) metal-oxide-semiconductor field effect transistors (MOSFETs) was investigated using atom probe tomography, based on the annealing time dependence of dopant distribution at 900°C.
Abstract: The dopant (P and B) diffusion path in n- and p-types polycrystalline-Si gates of trench-type three-dimensional (3D) metal-oxide-semiconductor field-effect transistors (MOSFETs) were investigated using atom probe tomography, based on the annealing time dependence of the dopant distribution at 900 °C. Remarkable differences were observed between P and B diffusion behavior. In the initial stage of diffusion, P atoms diffuse into deeper regions from the implanted region along grain boundaries in the n-type polycrystalline-Si gate. With longer annealing times, segregation of P on the grain boundaries was observed; however, few P atoms were observed within the large grains or on the gate/gate oxide interface distant from grain boundaries. These results indicate that P atoms diffuse along grain boundaries much faster than through the bulk or along the gate/gate oxide interface. On the other hand, in the p-type polycrystalline-Si gate, segregation of B was observed only at the initial stage of diffusion. After f...
22 citations
TL;DR: In this paper , the degradation of the liquid electrolyte and Si electrode and their interface were investigated using the latest developments in cryo-atom probe tomography, and it was shown that Si anode corrosion from the decomposition of the Li salt before charge-discharge cycles even begin.
Abstract: To advance the understanding of the degradation of the liquid electrolyte and Si electrode, and their interface, we exploit the latest developments in cryo-atom probe tomography. We evidence Si anode corrosion from the decomposition of the Li salt before charge–discharge cycles even begin. Volume shrinkage during delithiation leads to the development of nanograins from recrystallization in regions left amorphous by the lithiation. The newly created grain boundaries facilitate pulverization of nanoscale Si fragments, and one is found floating in the electrolyte. P is segregated to these grain boundaries, which confirms the decomposition of the electrolyte. As structural defects are bound to assist the nucleation of Li-rich phases in subsequent lithiations and accelerate the electrolyte’s decomposition, these insights into the developed nanoscale microstructure interacting with the electrolyte contribute to understanding the self-catalyzed/accelerated degradation Si anodes and can inform new battery designs unaffected by these life-limiting factors.
6 citations
TL;DR: In this article, the surface of highly phosphorus-doped polysilicon films produced by low pressure chemical vapour deposition (LPCVD) was investigated using scanning tunneling microscopy (STM) in air.
4 citations
TL;DR: In this article, the authors applied intense visible light irradiation to polycrystalline Si-thin polysilicon on glass substrates, which exhibited strong absorption features due to their amorphization by the application of a large implantation dose.
Abstract: Intense visible light irradiation was applied to phosphorous-implanted polycrystalline Si thin films on glass substrates, whichexhibited strong absorption features due to their amorphization by the application of a large implantation dose. Despite the shortpulsedurationofthevisiblelight,theuseofahigh-poweredandsubsequentlyintensifiedXearclampallowedforsignificantelectricalactivation even at near-ambient temperatures and above, surpassing the efficacy of conventional thermal activation processes. Usinga simple optical-thermal model, theoretical predictions indicate that the instantaneous temperatures of the phosphorous-implantedSi thin films reach approximately 680
3 citations
TL;DR: In this article, the effect of P or B predoping on As diffusion in polycrystalline Si was investigated by atom probe tomography, and the results suggest that As grain-boundary diffusion can be controlled by varying the local concentration of P and B.
Abstract: The effect of P or B predoping on As diffusion in polycrystalline Si was investigated by atom probe tomography. In all samples, a high concentration of As was found at grain boundaries, indicating that such boundaries are the main diffusion path. However, As grain-boundary diffusion was suppressed in the B-doped sample and enhanced in the P-doped sample. In a sample codoped with both P and B, As diffusion was somewhat enhanced, indicating competition between the effects of the two dopants. The results suggest that As grain-boundary diffusion can be controlled by varying the local concentration of P or B.
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85 citations
TL;DR: Hall mobility of polycrystalline silicon was measured in the dark and under illuminated conditions as discussed by the authors, and the free carrier concentration of 5×1015 cm−3 was not affected by illumination, and the room temperature mobility in 1mm grain size material after barrier elimination with light was 900 cm2/V
Abstract: Hall mobility of polycrystalline silicon was measured in the dark and under illuminated conditions. Grain boundary potential barriers present in the dark can be eliminated with light. When the barriers are removed, the mobility between 200 and 400 K is found to vary as T−2, which is the dependence observed in single crystals for the same order of magnitude of doping. The free‐carrier concentration of 5×1015 cm−3 was not affected by illumination, and the room temperature mobility in 1‐mm grain size material after barrier elimination with light was 900 cm2/V sec. A phenomological theory of Hall mobility in polycrystallllne silicon which explains these observations is presented.
60 citations
TL;DR: In this paper, the current components associated with the grain boundaries of diffused p/n junction polysilicon solar cells made on n- and p-type Wacker substrates were analyzed and experimentally identified.
Abstract: The current components associated with the grain boundaries of diffused p/n junction polysilicon solar cells made on n- and p-type Wacker substrates are analyzed and experimentally identified. New electrical methods for determining the presence or absence of preferential diffusion along the grain boundaries and for determining the average doping density of preferentially diffused regions along the grain boundaries are described. For p-type substrates, these methods revealed preferential phosphorus diffusion along grain boundaries; no preferential boron diffusion along grain boundaries was observed. The recombination current components were analyzed for the cells in which preferential diffusion occurred. The analysis shows that the dominant current component at small bias levels (0-300 mV) is the recombination current at the grain boundaries within the p/n junction space-charge region. At higher bias levels ( V \simeq V_{OC} \simeq 500-600 mV), both this current component and the current component due to recombination at that part of the grain boundary below the preferentially diffused region are important. The grain-boundary shunt resistance does not contribute a significant current component. It is shown that the preferential diffusion makes negligible the recombination current injected into the sidewall of the preferentially diffused region. This is consistent with a model in which the phosphorus diffusion significantly lowers the surface recombination velocity at the grain boundaries and in which the retarding built-in electric field further decreases the recombination current.
38 citations
TL;DR: The preferential diffusion of phosphorus down grain boundaries in cast polysilicon wafers has been studied using angle polishing followed by measuring junction depth by staining or e−beam-induced current as discussed by the authors.
Abstract: The preferential diffusion of phosphorus down grain boundaries in cast polysilicon wafers has been studied using angle polishing followed by measuring junction depth by staining or e‐beam†induced current. Data show that at 1040 °C the grain boundary diffusion parameter is 8000 × larger than the bulk diffusion coefficient (DBulk = 3.3×10−13cm2/s). During normal diffusion for 40 min at 1040 °C, a junction was created at 1.8 μm within the grain itself, but at the grain boundary the junction region extended ∠6 μm into the wafer. Concentration profiles near the grain boundary were calculated and compared to electrical response data for similar grain boundaries. In addition, the effects of heating polycrystalline wafers without a source of phosphorus at the surface was calculated, and it was concluded that lateral inhomogeneities of the dopant concentration, which may degrade solar cell performance, will exist both with and without a constant source of phosphorus for diffusion.
30 citations
TL;DR: In this article, a two-dimensional diffusion model is used to find effective grain (Dg) and grain-boundary (Dgb) diffusion coefficients, which leads to Dgb ≤ 10Dg, which is significantly lower than what has been deduced from conventional, larger grained polysilicon.
Abstract: The diffusion of phosphorus in crystallized amorphous Si layers was studied with secondary‐ion mass spectroscopy. A two‐dimensional diffusion model is used to find effective grain (Dg) and grain‐boundary (Dgb) diffusion coefficients. This simplified model leads to Dgb ≤ 10Dg, which is significantly lower than what has been deduced from conventional, larger grained polysilicon. Our result is consistent with specific‐gravity measurements, which found a significantly lower ‘‘mass defect’’ for layers deposited amorphous and subsequently crystallized as compared to initially polycrystalline layers.
29 citations