Following on the previous blog… 

Another way of looking at the role of semiconductors and semiconductor devices is from the point of view of fundamental principle of energy conservation and ability of the material serving as a medium allowing exchange between various forms of energy. The machines, instruments, or devices we conceive, are constructed and used primarily for the purpose of energy exchange/manipulation  obeying the principle of energy conservation in the process.

Semiconductors, strictly speaking devices operation of which is based on the properties of semiconductor materials, allow versatility in exchange between various forms of energy unattainable with either metals or insulators

Properly configured devices based on semiconductor materials are unique in this regard allowing manipulation of electric energy associated with a flow of electric charge carriers (transistors for instance), exchange of electric energy into light (light emitting diodes), energy of light (energy electromagnetic radiation) into electric energy (image sensors, solar cells), thermal energy into electric energy (thermistors), and so on. And that’s what makes semiconductors so special.