Semiconductors are of enormous technological importance because of their special properties, which can be modified by doping. Some applications include:
Thermistors
The resistivity of semiconductors varies with temperature. This enables semiconductors to be used as thermometers. Through doping the appropriate sensitivity in the required ranges can be obtained.
Hall Probes
These measure magnetic field strengths by using a small piece of semiconductor with known properties. By measuring the induced Hall voltage in an unknown magnetic field we can find B using:
IR Sensors/Optoelectronic devices
Optoelectronic devices are capable of sensing or responding to light of various wavelengths. This is due to the phenomenon of photo-conductivity whereby a semiconductor can greatly increase its electrical conductivity if the radiation has sufficient energy to promote electrons across the band gap. Many different semiconductors are available with different band gaps to suit particular applications.
Semiconductor devices
These involve junctions of p, i and n-type material. There are many types of devices including diodes, transistors, FETs, LEDs, solar cells, etc.