Govt. Exams
P-type semiconductors are doped with acceptor impurities which create holes as majority carriers. Electrons become minority carriers in p-type material.
Germanium has a bandgap of approximately 0.66 eV at room temperature (300K), making it a narrow bandgap semiconductor compared to silicon (1.1 eV).
In an intrinsic semiconductor, every electron-hole pair is generated together, so the concentration of free electrons equals the concentration of holes, both equal to the intrinsic carrier concentration n_i.
The built-in potential (V₀) develops naturally across a p-n junction due to diffusion of charge carriers. For silicon at 300 K, V₀ ≈ 0.7 V, independent of external voltage.
The intrinsic carrier concentration (ni) of silicon at 300 K is approximately 1.5 × 10^10 cm^-3, which is a standard value used in semiconductor calculations.
Photoconductivity is the increase in conductivity when photons with E > Eg create electron-hole pairs, increasing charge carrier concentration.
In active mode, BE junction is forward biased (injects carriers) while BC junction is reverse biased (collects carriers).
Zener diodes are operated in reverse bias within the zener breakdown region to maintain constant voltage across them, useful for voltage regulation.
Donor doping creates an n-type semiconductor, shifting the Fermi level closer to the conduction band due to increased electron concentration.
Germanium has a band gap of ~0.66 eV at room temperature, making it a narrow band gap semiconductor used in infrared applications.
