HARD
12th Uttar Pradesh Board
IMPORTANT
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Carbon, silicon and germanium have four valence electrons each. At room temeprature which one of the following statements is most appropriate?

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Important Questions on Semiconductor Electronics: Materials, Devices and Simple Circuits

EASY
12th Uttar Pradesh Board
IMPORTANT
Identify the property which is not a characteristics for a semiconductor,
MEDIUM
12th Uttar Pradesh Board
IMPORTANT
Determine the conductivity and resistivity of pure germanium at 300 K, assuming that at this temperature the concentration of germanium is 2.5×1013 cm-3 The electron and hole mobilities are 3600 cm2V-1s-1 and 1700 cm2V-1s-1, respectively. Take, 1.6×10-19 C.
MEDIUM
12th Uttar Pradesh Board
IMPORTANT
A sample of germanium is doped to the extent of 1014 donor atoms per cm3 and 7×1013 acceptor atoms per cm3. The resistivity of pure germanium at the temperature of the sample is 60Ωcm. Find the total conduction current density due to an applied electric field of 2 Vcm-1. The electron and hole mobilities are given to be 3800 cm2V-1s-1 and 1800 cm2V-1s-1, respectively. Take, e = 1.6×10-19 C.
MEDIUM
12th Uttar Pradesh Board
IMPORTANT
The energy gap in germanium is 0.75 eV. Compare the intrinsic conductivity of germanium at 300 K and 330 K. Take kB=8.6×10-5 eVK-1.
MEDIUM
12th Uttar Pradesh Board
IMPORTANT
In an intrinsic semiconductor the energy gap Eg is 1.2 eV. Its hole mobility is much smaller than electron mobility and independent of temperature. What is the ratio between conductivity at 600 K and that at 300 K? Assume that the temperature dependence of intrinsic carrier concentration ni is given by ni=n0exp-Eg2kBT where n0 is a constant.
MEDIUM
12th Uttar Pradesh Board
IMPORTANT
The energy gap of a semiconductor is 1.10 eV The maximum wavelength (in A°) at which it starts energy absorption will be
EASY
12th Uttar Pradesh Board
IMPORTANT
EC, Ev and EF are conduction band, valence band and forbidden energy gap, respectively, for a solid. If lattice constant increases, then