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In a p-n junction, the depletion region is 400 nm wide and an electric field of \( \rm 5 \times 10 ^{5} Vm^{-1} \) exists in it. (a) Find the height of the potential barrier. (b) What should be the minimum kinetic energy of a conduction electron which can diffuse from the n-side to the p-side ?
The potential barrier existing across an unbiased p-n junction is 0.2 volt. What minimum kinetic energy a hole should have to diffuse from the p-side to the n-side if (a) the junction is unbiased, (b) the junction is forward-biased at 0.1 volt and (c) the junction is reverse-biased at 0.1 volt ?
In a p-n junction, a potential barrier of 250 meV exists across the junction. A hole with a kinetic energy of 300 meV approaches the junction. Find the kinetic energy of the hole when it crosses the junction if the hole approached the junction (a) from the p-side and (b) from the n-side.
When a p-n junction is reverse-biased, the current becomes almost constant at 25 μA. When it is forward-biased at 200 mV, a current of 75 μA is obtained. Find the magnitude of diffusion current when the diode is (a) unbiased, (b) reverse-biased at 200 mV and (c) forward-biased at 200 mV.
The drift current in a p-n junction is 20.0 μA. Estimate the number of electrons crossing a cross section per second in the depletion region.
The current–voltage characteristic of an ideal p-njunction diode is given by \[ \rm i = i_{0} ( e^{\frac{eV}{kT}} - 1 ) \] where the drift current \( \rm i_{0} \) equals 10 μA. Take the temperature T to be 300 K. (a) Find the voltage \( \rm V_{0} \) for which \( \rm e^{\frac{eV}{kT}} \) = 100. One can neglect the term 1 for voltages greater than this value. (b) Find an expression for the dynamic resistance of the diode as a function of V for \( \rm V > V_{0} \). (c) Find the voltage for which the dynamic resistance is 0.2 Ω.
Consider a p-n junction diode having the characteristic \[ \rm i = i_{0} ( e^{\frac{eV}{kT}} - 1 ) \] where \( \rm i_{0} \) = 20 μA. The diode is operated at T = 300 K. (a) Find the current through the diode when a voltage of 300 mV is applied across it in forward bias. (b) At what voltage does the current double?
Calculate the current through the circuit and the potential difference across the diode shown in figure (45-E1). The drift current for the diode is 20 μA.
Each of the resistances shown in figure (45-E2) has a value of 20 Ω. Find the equivalent resistance between A and B. Does it depend on whether the point A or B is at higher potential?
Find the currents through the resistances in the circuits shown in figure (45-E3).
What are the readings of the ammeters A1 and A2 shown in figure (45-E4). Neglect the resistances of the meters.
Find the current through the battery in each of the circuits shown in figure (45-E5).
Find the current through the resistance R in figure (45-E6) if (a) R = 12 Ω (b) R = 48 Ω.
Draw the current–voltage characteristics for the device shown in figure (45-E7) between the terminals A and B.
Find the equivalent resistance of the network shown in figure (45-E8) between the points A and B.
When the base current in a transistor is changed from 30 μA to 80 μA, the collector current is changed from 1.0 mA to 3.5 mA. Find the current gain β.
A load resistor of 2 k Ω is connected in the collector branch of an amplifier circuit using a transistor in common-emitter mode. The current gain β = 50. The input resistance of the transistor is 0.50 kΩ. If the input current is changed by 50 μA, (a) by what amount does the output voltage change, (b) by what amount does the input voltage change and (c) what is the power gain?
Calculate the number of states per cubic metre of sodiumin 3s band. The density of sodium is \( \rm 10^{13} kgm^{-3} \). How many of them are empty ?
In a pure semiconductor, the number of conduction electrons is \( \rm 6 \times 10 ^{19} \) per cubic metre. How many holes are there in a sample of size 1 cm × 1 cm × 1 mm ?
Indium antimonide has a band gap of 0.23 eV between the valence and the conduction band. Find the temperature at which kT equals the band gap.