How are diodes produced?

Answer 1

In the simplest method, you can start with a doped semiconductor substrate, such as p-type Silicon. You can then grow a native oxide layer (SiO2) on top of the substrate. Then, you can use photolithography (with photoresist and masks) to create a window in the oxide. The substrate is then placed into a high-temperature furnace where a dopant, in this case n-type such as P, is flowed past the substrate. The P is in some gas phase and may be bonded to other atoms, but a reaction occurs causing the P to enter the Semiconductor and diffuse into the semiconductor. This creates a p-n junction. Contacts can then be placed on the appropriate materials.

Of course, this is a very basic description that you will find in any textbook. In modern day diodes, there is a lot more technology and device structures that improve the performance dramatically.