The thermistor is, as the name implies, a temperature-sensitive resistor
its terminal resistance is related to its body temperature. Most thermisu that
: Thermistor are made by heating under
semiconductor ceramic materials made up from the mixture
cobalt, copper, nickel, iron etc.
Solar cell consists of p-type and n-type semiconductor material forming a p-n
unction. The surface layer is made of p-type material. It has maximum
easily reach the pn junction. The doping level of p-doped semiconductor is
very high. A small metal contact of nickel plated ring along the edge of the
upper surface of p-type material acts as the positive output terminal called
anode. The metal contact at the bottom of n-type material acts as the negative
output terminal called cathode.
photons collide with the valance electrons and impart them sufficient energy.
are generated on both sides of the junction. In p-type region, the newly
generated electrons are minority carriers. In n-type region, the newly
ECnerated holes are minority carriers. As we have learned in the theory of p-n
Junction diode, the electric field set up in the vicinity of junction, attracts the
ority carriers electrons from p-type to n-type and minority carriers holes
ype to p-type. In this way, electrons and holes move freely across the
10a is connected as shown in the above Figure-15, current flows
rough it. This urrent is called photocurrent.
the resistance and make the terminals open), the voltage across
gative terminals is the open circuit voltage of the solar cell.
Cnt and open circuit voltage both are directly proportional to
he positive and neg
the surface area being illuminated.
varactor diode is in pF range, it is suitable for use in high-frequen
lts main applications are
- Automatic frequency control device
- FM modulator
- Adjustable band pass filter
- Paiametric amplitier