Activation energy of source-drain current in hydrogenated and unhydrogenated polysilicon thin-film transistors

Khan, Babar A.; Pandya, R.

doi:10.1109/16.55761

Cited by 58 publications

(16 citation statements)

References 11 publications

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“…In particular, we measured τ eff = 4.6 ms, J 0 = 14.5 fA/cm 2 , and iV OC > 700 mV. Sample n3 benefits from the FGA treatment owing to the diffusion of H + atoms into the stack, enhancing chemical passivation at the c‐Si/SiO 2 interface . Similar results about FGA have been reported in Peibst et al, although in our case, the implantation dose is higher than typical literature values with similar annealing conditions.…”

Section: Resultssupporting

confidence: 88%

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Limodio

Yang

Groot

et al. 2020

Progress in Photovoltaics

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In this work, we develop SiOx/poly‐Si carrier‐selective contacts grown by low‐pressure chemical vapor deposition and boron or phosphorus doped by ion implantation. We investigate their passivation properties on symmetric structures while varying the thickness of poly‐Si in a wide range (20‐250 nm). Dose and energy of implantation as well as temperature and time of annealing were optimized, achieving implied open‐circuit voltage well above 700 mV for electron‐selective contacts regardless the poly‐Si layer thickness. In case of hole‐selective contacts, the passivation quality decreases by thinning the poly‐Si layer. For both poly‐Si doping types, forming gas annealing helps to augment the passivation quality. The optimized doped poly‐Si layers are then implemented in c‐Si solar cells featuring SiO2/poly‐Si contacts with different polarities on both front and rear sides in a lean manufacturing process free from transparent conductive oxide (TCO). At cell level, open‐circuit voltage degrades when thinner p‐type poly‐Si layer is employed, while a consistent gain in short circuit current is measured when front poly‐Si thickness is thinned down from 250 to 35 nm (up to +4 mA/cm2). We circumvent this limitation by decoupling front and rear layer thickness obtaining, on one hand, reasonably high current (JSC‐EQE = 38.2 mA/cm2) and, on the other hand, relatively high VOC of approximately 690 mV. The best TCO‐free device using Ti‐seeded Cu‐plated front contact exhibits a fill factor of 75.2% and conversion efficiency of 19.6%.

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Section: Resultssupporting

confidence: 88%

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Limodio

Yang

Groot

et al. 2020

Progress in Photovoltaics

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“…In heavily doped samples, activation energy is proportional to barrier height, and carrier mobility is inversely, exponentially proportional to barrier height. [7][8][9] The presented data are consistent with the theory's predicted effects of grain sizes and activation energies on carrier mobilities.…”

Section: Resistivity Of Boron and Phosphorus Doped Polycrystalline Sisupporting

confidence: 86%

Resistivity of boron and phosphorus doped polycrystalline Si1−xGex films

Bang

Cao

Wang

et al. 1995

Applied Physics Letters

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Sheet resistance, Hall mobility, and effective carrier concentration as a function of annealing parameters for boron or phosphorus ion implanted films of polycrystalline Si, Si0.75Ge0.25, and Si0.50Ge0.50 films are presented. The films were ion implanted with boron or phosphorus at dosages between 5×1014 and 4×1015 cm−2, and then thermally annealed between 550 and 650 °C from 0.25 to 120 min. Boron doped films showed decreasing minimum sheet resistance with increasing Ge fraction, while phosphorus doped films exhibited the reverse trend. Both boron and phosphorus doped films showed minima as a function of anneal time. This is attributed to the competing processes of damage annealing versus dopant segregation. Poly-Si0.50Ge0.50 films achieved minimum resistance faster than poly-Si films, and the lowest sheet resistances were measured in boron doped, poly-Si0.50Ge0.50 films.

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“…͑a͒ Each GB barrier potential curve has a peak around V gs at I ds ϭ10 nA ͑Table I͒, which is a little larger than V th defined in C -V characteristics. This feature is not observed in the activation energy of conductance 18 and looks like the one shown in Fig. 1 described by Eqs.…”

Section: B Evaluation Of the Gb Trap State Densitiesmentioning

confidence: 60%

Evaluation of grain boundary trap states in polycrystalline–silicon thin-film transistors by mobility and capacitance measurements

Ikeda¹

2002

Journal of Applied Physics

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A method for evaluating localized grain boundary (GB) trap states in polycrystalline–silicon thin-film transistors (poly-Si TFTs) is proposed. Field effects in poly-Si TFTs are analyzed by decomposition of the two-dimensional Poisson’s equation. This analysis gives the theoretical basis for evaluating the localized GB trap state density. The trap states are evaluated with the GB barrier potential given by the activation energy of the effective mobility and with the surface potential calculated from the capacitance–voltage characteristics in poly-Si TFTs. This evaluating method was applied to several different types of poly-Si TFTs fabricated with excimer laser annealing crystallization processes. This method has succeeded experimentally in eliminating the error effects related to oxide–semiconductor interface trap states and in clarifying that the GB barrier potential has a peak in its gate bias dependence. This method has also elucidated that the GB trap state density has almost the same value independent of the grain size when the hydrogenation efficiency in poly-Si is in the same level between TFTs. The good agreement of the simulated and the measured drain currents confirm the validity of this method.

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Activation energy of source-drain current in hydrogenated and unhydrogenated polysilicon thin-film transistors

Cited by 58 publications

References 11 publications

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

Resistivity of boron and phosphorus doped polycrystalline Si1−xGex films

Evaluation of grain boundary trap states in polycrystalline–silicon thin-film transistors by mobility and capacitance measurements

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