Semiconductor Electronics Materials Devices And Simple Circuits

In -type doping, the impurities have left holes in the atomic structure which tend to attract and hold free electrons; This pulls the fermi level down until it gets close to the valence bond. Hence, name of level formed due to impurity atom is -type in the forbidden gap is acceptor level.

When the reverse voltage across a zener diode exceeds the breakdown voltage the current increases very sharply. In this region, the curve is almost vertical. It means voltage across zener diode is constant at even though the current through it changes. Therefore, a zener diode behaves as a constant voltage source.

When junction diode is forward biased, more number of charge carriers (electrons in n-side and holes in -side) moves through the junction. Therefore, in forward biasing barrier potential is reduced. Thus, increasing the current in the circuit.

At there is no free electrons for conduction. Therefore, at an intrinsic semiconductor behaves as insulator.

In a transistor, the base is an extrinsic semiconductor.

Answer (b) NOT gate

The reverse saturation current is the order of micro-ampere .

Truth table is of gate.

Gas is a semiconductor.

We know
Given So,

Zener diode is used as voltage regulator.

In an transistor, base ( -type material) is sandwiched between two -type materials.

Due to application of forward biased voltage, the length of depletion region decreases and vice versa. Thus, decrease in forward biased voltage increases the length of depletion region.

Bismuth is the pentavalent impurity, hence it can be used as dopant to obtain -type semiconductor

Zener breakdown occurs in zener diode when reverse biased voltage applied to the diode is increased beyond a certain level which results in generating strong electric field

Bond breaks due to increase in temperature. Thus, density of electrons and holes increases. Relaxation time decreases due to rapid collisions