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As a material transitions from the amorphous state to the fully crystalline state, the broad maximum sharpens up and other sharp peaks start to appear in the n(λ) and k(λ) spectra. This is demonstrated for the case of amorphous silicon progressing to poly-silicon and further progressing to crystalline silicon.
Amorphous silicon (a-Si) is the non-crystalline form of silicon used for solar cells and thin-film transistors in LCDs.. Used as semiconductor material for a-Si solar cells, or thin-film silicon solar cells, it is deposited in thin films onto a variety of flexible substrates, such as glass, metal and plastic.
A reported silicon phosphide is Si 12 P 5 (no practical applications), [89] [90] formed by annealing an amorphous Si-P alloy. The arsenic–silicon phase diagram measured at 40 Bar has two phases: SiAs and SiAs 2. [91] The antimony–silicon system comprises a single eutectic close to the melting point of Sb. [92] The bismuth system is a ...
A compound semiconductor is a semiconductor compound composed of chemical elements of at least two different species. These semiconductors form for example in periodic table groups 13–15 (old groups III–V), for example of elements from the Boron group (old group III, boron, aluminium, gallium, indium) and from group 15 (old group V, nitrogen, phosphorus, arsenic, antimony, bismuth).
Crystalline silicon has a metallic luster and a grayish color. Single crystals can be grown with the Czochralski process. Crystalline silicon can be doped with elements such as boron, gallium, germanium, phosphorus or arsenic. Doped silicon is used in solid-state electronic devices, such as solar cells, rectifiers and computer chips. [1]
Polycrystalline silicon, or multicrystalline silicon, also called polysilicon, poly-Si, or mc-Si, is a high purity, polycrystalline form of silicon, used as a raw material by the solar photovoltaic and electronics industry. Polysilicon is produced from metallurgical grade silicon by a chemical purification process, called the Siemens process.
The aluminum that diffuses into the amorphous silicon is believed to weaken the hydrogen bonds present, allowing crystal nucleation and growth. [48] Experiments have shown that polycrystalline silicon with grains on the order of 0.2–0.3 μm can be produced at temperatures as low as 150 °C.
Aluminum-silicon phase diagram. Aluminum forms a eutectic with silicon, which is at 577 °C, with a Si content of 12.5% [7] or 12.6%. [8] Up to 1.65% Si can be dissolved in aluminum at this temperature. However, the solubility decreases rapidly with temperature. At 500 °C it is still 0.8% Si, at 400 °C 0.3% Si and at 250 °C only 0.05% Si.