Metal–semiconductor junction

Have you ever played with magnets and noticed how they attract certain materials like paper clips? Well, metals are like magnets, but instead of attracting paper clips, they attract electrons (tiny negatively charged particles).

Now, have you ever rubbed a balloon on your hair or clothes and then stuck it on a wall? This happens because the balloon became charged with static electricity (a buildup of electric charge in one place) and the wall had the opposite charge, so they stuck together.

In a metal-semiconductor junction, a metal and a semiconductor material (similar to the material used in computer chips) are brought together. Just like the balloon and the wall, the metal and semiconductor can have opposite charges. When this happens, the metal pulls away some of the semiconductor's electrons and becomes negatively charged.

This can create a barrier or "hill" that prevents electrons from easily passing from one side to the other. But, if the semiconductor is changed in a certain way (doped), it can become more conductive and electrons can move more easily across the "hill".

This effect is useful in creating different electronic components like diodes or transistors, which are important in many electronic devices like your phone or computer.