Semiconductor Electronics: Materials, Devices and Simple Circuits Chapter-Wise Test 2

A half-wave rectifier conducts only during the positive half-cycle of the AC input, so the output frequency remains the same as the input frequency (e.g., 50 Hz input gives 50 Hz output).

A full-wave rectifier converts both AC half-cycles to DC, producing a pulsating DC output with peaks corresponding to the input waveform, not steady without a filter.

The reverse current remains small (\( \mu \text{A} \)) until the reverse bias reaches the breakdown voltage (\( V_{br} \)), where it increases sharply due to junction breakdown.

In reverse bias, the small current (\( \mu \text{A} \)) is due to minority carriers (electrons in p-side, holes in n-side) drifting across the junction under the electric field.

A p-type semiconductor is created by doping a tetravalent semiconductor (e.g., Si) with a trivalent impurity (e.g., B, Al, In), which accepts electrons and creates holes as majority carriers.

Semiconductor diodes are small, low-power, operate at low voltages, and have long life and high reliability compared to bulky, high-power vacuum tubes.

Diffusion current arises from the movement of carriers (holes from p-side to n-side, electrons from n-side to p-side) due to concentration gradients across the junction during its formation.

The depletion region forms due to diffusion of electrons and holes across the junction, leaving behind immobile ionized impurities that create a space-charge region.

Pentavalent dopants (valency 5) include P, As, and Sb. Indium (In) is trivalent (valency 3) and used for p-type doping, not n-type.

In a half-wave rectifier, the diode is forward biased and conducts only during the positive half-cycle of the AC input, blocking the negative half-cycle.