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Interactives

Periodic Puzzle

Periodic Table:

The periodic table is a chart of all the atoms currently known. The chart is carefully organized: each atom is listed in order of how many protons it has and in such a way that elements in each column have similar characteristics. For example, on the far right of the periodic table all the elements are gases, known as Noble Gases, which don't mix easily with other materials. On the bit of the chart shown in the periodic puzzle, silicon (Si) and germanium (Ge) (shown in the color red) are both in the same column and are both semiconductors -- materials which can be made to conduct electricity or not as needed. To grow the crystals in the heart of a transistor, chemists mix in elements from nearby columns to make a material with the proper conductivity.

Wafer Maker

Forming Crystals:

One of the toughest problems on the road to commercial transistors was growing semiconductor crystals. To work, the crystal needed precise layers of different kinds of semiconductors (known as N-type and P-type). An early way to do this was to dip a seed crystal into a melt of germanium or silicon and to slowly pull it out as a crystal formed around the seed. Materials were added to the melt during the process, so the final crystal was made of the right kinds of layers. Just like in this game, the right temperature and speed were crucial for a perfect finished product.

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