# Why can a non-Metalloid be a Semiconductor?

I was reading that the first description of a semiconductor material was made by Michael Faraday in 1833 and published in Experimental Researches in Electricity.-Fourth Series (https://www.computerhistory.org/siliconengine/first-semiconductor-effect-is-recorded/). He noticed electrical conduction increasing with temperature in Silver Sulfide ($$Ag_2 S$$) crystals.

Here is a periodic table classifying the elements as metals, nonmetals and metalloids

I don't know much about solid state physics, but for some reason I thought that the only elements that could be used as semiconductors were those that are in the metalloid staircase. Silver Sulfide is made of Silver (a metal) and Sulfur (a non-metal). How is it that the combination of these elements is a semiconductor? Is it possible to make semiconductors from the combinations of any metal and non-metal element? if it's possible, why is it that transistors are mostly made of Silicon and Germanium instead of different varieties of combinations of this kind?

• Alloys may not be easily related to their elemental composition. Many 3-5 and 2-6 compounds are semiconductors like GaAs and HgTe. Welcome to solid state physics. May 15 at 22:53