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.
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.