GATE 1989 Video Solutions on EDC (Electronic Devices and Circuits)

1.       Due to illumination by light, the electron and hole concentrations in a heavily doped N-type semiconductor increases by Δn and Δp respectively, if ni is the intrinsic carrier concentration then
a.       Δn < Δp
b.      Δn > Δp
c.       Δn = Δp
d.      Δn x Δp = ni2
                 Solution :

2.       The concentration of ionized acceptors and donors in a semiconductor are NA, ND respectively. If NA > ND and ni is the intrinsic  concentration, then the position of the Fermi level with respect to the intrinsic level depends on
a.       NA – ND
b.      NA + ND
c.       (NA x ND) / ni2
d.      ni
                 Solution :

3.       The switching speed of P+N junction depends primarily on
a.       the mobility of minority carriers in the P+ region
b.      the lifetime of minority carriers in the P+ region
c.       the mobility of majority carriers in the N region
d.      the lifetime of majority carriers in the N region
                 Solution :

4.       In a Zener diode,
a.       only P-region is heavily doped
b.      only N-region is heavily doped
c.       both P and N-regions are heavily doped
d.      both P and N-regions are lightly doped
                 Solution :

5.       In a MOSFET, the polarity of the inversion layer is the same as that of the
a.       Charge on the gate electrode
b.      Minority carriers in the drain
c.       Majority carriers in the substrate
d.      Majority carriers in the source
                 Solution :

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