Govt. Exams
Entrance Exams
VT = kT/q where k=1.38×10⁻²³ J/K, T=300K, q=1.6×10⁻¹⁹C gives approximately 26 mV or 25 mV.
In saturation, both BE and BC junctions are forward biased, resulting in VCE dropping to approximately 0.2-0.3V for silicon transistors.
In intrinsic semiconductors, thermally generated electrons and holes are in equal numbers, making ni = pi at thermal equilibrium.
Reverse bias widens the depletion region by pulling majority carriers away from the junction, increasing the width of the space charge region.
Germanium has Eg ≈ 0.66 eV at 300K, lowest among common semiconductors; causes high intrinsic carrier concentration and leakage current.
Forward bias injects minority carriers; their recombination releases energy as photons (electroluminescence) in direct bandgap semiconductors.
Zener diodes operate in reverse breakdown region maintaining nearly constant voltage for voltage regulation applications.
N-channel enhancement mode MOSFETs require positive gate voltage to create inversion layer for conduction.
MOSFETs have fastest switching due to voltage-controlled operation without minority carrier storage effects.
LEDs emit light through electroluminescence when forward biased with sufficient current. The energy of emitted photons equals the bandgap energy of the semiconductor material.
