Govt. Exams
Entrance Exams
Reverse bias voltage adds to the built-in potential, increasing the total electric field and widening the depletion region further.
Threshold voltage VT is when the surface band bending creates an inversion layer, transition from depletion to strong inversion.
Output impedance Zo ≈ Rc || RL (Rc in parallel with load resistance), depending on collector circuit configuration.
Increasing minority carrier lifetime improves efficiency by reducing recombination losses. Other options reduce efficiency.
Transconductance gm ∝ W/L (width-to-length ratio), so decreasing channel length L increases transconductance.
Hall coefficient is positive for p-type (hole conduction) and negative for n-type (electron conduction), based on the sign of majority carriers.
The energy of emitted photons equals the band gap energy (E = Eg = hc/λ), determining the color/wavelength of LED light.
When metal work function > semiconductor work function, electrons transfer from semiconductor to metal, creating a Schottky barrier.
Semiconductors have negative temperature coefficient because increased temperature increases intrinsic carrier concentration, decreasing resistance.
Einstein relation: D/μ = kT/e. At room temperature (300K), this thermal voltage ≈ 26 mV. This fundamental relation connects drift and diffusion processes in semiconductors.
