Electronic Devices Chapter-Wise Test 1

Holes diffuse from p-side to n-side, leaving behind immobile negative ionized acceptors on the p-side, forming the negative space-charge region of the depletion layer.

In forward bias, current flows from p-side (positive) to n-side (negative) conventionally, as indicated by the diode symbol’s arrow, due to the flow of majority carriers.

The capacitor charges to the peak voltage and discharges through the load resistor (\( R_L \)) during the non-conducting half-cycle, smoothing the output voltage.

Si (third orbit) and Ge (fourth orbit) are group IV elements, each with four valence electrons (2s and 2p for Si, 4s and 4p for Ge), forming covalent bonds in their lattice.

In forward bias, the applied voltage reduces the barrier height, allowing minority carriers to cross the junction and diffuse, resulting in a current (in mA) due to diffusion of holes and electrons.

Insulators have a large energy gap (\( E_g > 3 \, \text{eV} \)), preventing electron excitation, while semiconductors have a smaller gap (\( 0.2 \, \text{eV} \) to \( 3 \, \text{eV} \)), allowing some conduction.

During junction formation, electrons diffuse from n-side to p-side, leaving behind immobile positive ionized donors on the n-side, forming the positive space-charge region.

Doping introduces impurities (pentavalent or trivalent) that provide additional charge carriers (electrons or holes), significantly enhancing conductivity compared to intrinsic semiconductors.

The threshold voltage for a germanium diode, where forward current increases significantly, is approximately 0.2 V, lower than silicon due to its smaller energy gap.

The depletion region, formed by diffusion and drift, is very thin, on the order of one-tenth of a micrometer (\( 0.1 \, \mu \text{m} \)), due to the sharp transition at the junction.