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Read the following statements regarding semiconductor and mark the incorrect answer.
Semiconductors have ______ conduction band and ______ valence band.
Hole mobility in Ge at room temperature is 1900 cm^{2}/Vsec. The diffusion coefficient is ________cm^{2}/sec.
(Write answer to one decimal point.)
(Take kT = 25 mV)
The Difference between the donor energy level and fermi level in a ntype semiconductor in where 25% of the atoms are ionised at 300 k is:
A semiconductor with intrinsic carrier concentration 1 × 10^{10} cm^{3} at 300°K has both valence and conduction band effective densities of states N_{C} and N_{V} equal to 10^{19} cm^{3}. The band gap E_{g} is _____ eV. (Write answer to one decimal point.)
In a very long ptype Si bar with doping concentration N_{a} = 10^{17} cm^{3}, excess holes are injected such that excessive concentration of holes at x = 0 is 5 × 10^{16} cm^{3}. The hole concentration at x = 1 μm is _____ × 10^{17} cm^{3}. Take μ_{p} = 500 cm^{2}/vs and recombination time constant τ_{p} = 10^{8} s, kT = 0.0259 eV (Write answer to two decimal point.)
In an intrinsic semiconductor, the Fermi energy level EF doesn’t lie in the middle of the band gap cause:
A silicon bar is doped with donor impurities ND = 2.25 × 10^{15} cm^{3}. If the electron mobility μn = 1000 cm2/vs then the approximate value of resistivity of silicon bar assuming partial ionization of 55% is __________ (Ω  cm)
Holes are injected into ntype Ge so that the at the surface of the semiconductor hole concentration is 10^{14}/cm^{3}. If diffusion constant of a hole in Ge is 49cm^{2}/sec and minority carrier lifetime is τ_{p} = 10^{3} sec. Then the hole concentration Δp at a distance of 4mm from the surface is ______10^{14}/cm^{3}.
22 docs263 tests

22 docs263 tests
