Semiconductor Electronics — Class 12 Physics PYQs

When the resistance measured between p and n ends of a p-n junction diode is high, it can act as a/an –
(A) resistor
(B) inductor
(C) capacitor
(D) switch

When a p-n junction diode is forward biased
(A) the barrier height and the depletion layer width both increase.
(B) the barrier height increases and the depletion layer width decreases.
(C) the barrier height and the depletion layer width both decrease.
(D) the barrier height decreases and the depletion layer width increases.

Assertion (A) : We cannot form a p-n junction diode by taking a slab of a p-type semiconductor and physically joining it to another slab of a n-type semiconductor.
Reason (R) : In a p-type semiconductor ${\eta }_e>>{\eta }_h$ while in a n-type semiconductor ${\eta }_h>>{\eta }_e$.

Assertion (A) : In a semiconductor diode the thickness of depletion layer is not fixed.
Reason (R) : Thickness of depletion layer in a semiconductor device depends upon many factors such as biasing of the semiconductor.

A p-type Si semiconductor is made by doping an average of one dopant atom per $5\times 10^7$ silicon atoms. If the number density of silicon atoms in the specimen is $5\times 10^{28}$ atoms $m^{-3}$, find the number of holes created per cubic centimetre in the specimen due to doping. Also give one example of such dopants.

Draw circuit arrangement for studying V-I characteristics of a p-n junction diode.
(b) Show the shape of the characteristics of a diode.
(c) Mention two information that you can get from these characteristics.

What are majority and minority charge carriers in an extrinsic semiconductor ?
(b) A p-n junction is forward biased. Describe the movement of the charge carriers which produce current in it.
(c) The graph shows the variation of current with voltage for a p-n junction diode.
Estimate the dynamic resistance of diode at V = -0.6 volt.

Ge is doped with As. Due to doping,
(A) the structure of Ge lattice is distorted.
(B) the number of conduction electrons increases.
(C) the number of holes increases.
(D) the number of conduction electrons decreases.

An n-type semiconducting Si is obtained by doping intrinsic Si with :
(A) Al
(B) B
(C) P
(D) In

When a p-n junction diode is subjected to reverse biasing :
(A) the barrier height decreases and the depletion region widens.
(B) the barrier height increases and the depletion region widens.
(C) the barrier height decreases and the depletion region shrinks.
(D) the barrier height increases and the depletion region shrinks.