Matching Items (3)

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Electroplating of Aluminium on Silicon in an Ionic Liquid

Description

Electroplating of aluminum (Al) on silicon (Si) substrates has been demonstrated in an above-room-temperature ionic liquid for the metallization of wafer-Si solar cells. The electrolyte was prepared by mixing anhydrous

Electroplating of aluminum (Al) on silicon (Si) substrates has been demonstrated in an above-room-temperature ionic liquid for the metallization of wafer-Si solar cells. The electrolyte was prepared by mixing anhydrous aluminum chloride and 1-ethyl-3-methylimidazolium tetrachloroaluminate. The plating was carried out by means of galvanostatic electrolysis. The structural and compositional properties of the Al deposits were characterized, and the sheet resistance of the deposits revealed the effects of pre-bake conditions, deposition temperature, and post-deposition annealing conditions. It was found that dense, adherent Al deposits with resistivity in the high 10[superscript −6] Ω-cm range can be reproducibly obtained directly on Si substrates.

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Date Created
  • 2014-11-30

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Characterization of Al/Si junctions on Si(100) wafers with chemical vapor deposition-based sulfur passivation

Description

Chemical vapor deposition-based sulfur passivation using hydrogen sulfide is carried out on both n-type and p-type Si(100) wafers. Al contacts are fabricated on sulfur-passivated Si(100) wafers and the resultant Schottky

Chemical vapor deposition-based sulfur passivation using hydrogen sulfide is carried out on both n-type and p-type Si(100) wafers. Al contacts are fabricated on sulfur-passivated Si(100) wafers and the resultant Schottky barriers are characterized with current–voltage (I–V), capacitance–voltage (C–V) and activation-energy methods. Al/S-passivated n-type Si(100) junctions exhibit ohmic behavior with a barrier height of <0.078 eV by the I–V method and significantly lower than 0.08 eV by the activation-energy method. For Al/S-passivated p-type Si(100) junctions, the barrier height is ~0.77 eV by I–V and activation-energy methods and 1.14 eV by the C–V method. The discrepancy between C–V and other methods is explained by image force-induced barrier lowering and edge-leakage current. The I–V behavior of an Al/S-passivated p-type Si(100) junction remains largely unchanged after 300 °C annealing in air. It is also discovered that heating the S-passivated Si(100) wafer before Al deposition significantly improves the thermal stability of an Al/S-passivated n-type Si(100) junction to 500 °C.

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Date Created
  • 2014-09-01

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Development of silver-free silicon photovoltaic solar cells with all-aluminum electrodes

Description

To date, the most popular and dominant material for commercial solar cells is

crystalline silicon (or wafer-Si). It has the highest cell efficiency and cell lifetime out

of all commercial solar cells.

To date, the most popular and dominant material for commercial solar cells is

crystalline silicon (or wafer-Si). It has the highest cell efficiency and cell lifetime out

of all commercial solar cells. Although the potential of crystalline-Si solar cells in

supplying energy demands is enormous, their future growth will likely be constrained

by two major bottlenecks. The first is the high electricity input to produce

crystalline-Si solar cells and modules, and the second is the limited supply of silver

(Ag) reserves. These bottlenecks prevent crystalline-Si solar cells from reaching

terawatt-scale deployment, which means the electricity produced by crystalline-Si

solar cells would never fulfill a noticeable portion of our energy demands in the future.

In order to solve the issue of Ag limitation for the front metal grid, aluminum (Al)

electroplating has been developed as an alternative metallization technique in the

fabrication of crystalline-Si solar cells. The plating is carried out in a

near-room-temperature ionic liquid by means of galvanostatic electrolysis. It has been

found that dense, adherent Al deposits with resistivity in the high 10^–6 ohm-cm range

can be reproducibly obtained directly on Si substrates and nickel seed layers. An

all-Al Si solar cell, with an electroplated Al front electrode and a screen-printed Al

back electrode, has been successfully demonstrated based on commercial p-type

monocrystalline-Si solar cells, and its efficiency is approaching 15%. Further

optimization of the cell fabrication process, in particular a suitable patterning

technique for the front silicon nitride layer, is expected to increase the efficiency of

the cell to ~18%. This shows the potential of Al electroplating in cell metallization is

promising and replacing Ag with Al as the front finger electrode is feasible.

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Date Created
  • 2016