Questions and Answers
A P-type semiconductor has acceptor levels 57 meV above the valence band. What is the maximum wavelength of light required to create a hole?
What is the current in the circuit?
What should be the value of the resistor R, connected in series with the diode for obtaining maximum current?
For a transistor amplifier in common emitter configuration with a load impedance of 1 kΩ, what is the current gain if hfe = 50 and hoe = 25 μΑ/V?
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What will be the output voltage of the amplifier using an NPN transistor with current gain β = 100 in common emitter configuration?
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What type of semiconductor is indicated if the concentrations of electrons and holes are 8 × 10^18/m3 and 5 × 10^18/m, respectively, with mobilities of electrons and holes at 2.3 m2/volt-sec and 0.01 m2/volt-sec?
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Study Notes
Semiconductor Physics
- A P-type semiconductor with acceptor levels 57 meV above the valence band requires a minimum energy of light to create a hole, corresponding to a maximum wavelength of 217100 Å.
Current and Diodes
- The current in a circuit can be calculated by considering the voltage drop across a diode, which can have a constant voltage drop of 0.5 V at all currents.
- A diode with a maximum power rating of 100 milliwatts requires a series resistor with a value of 6.67 Ω to obtain maximum current.
Transistor Amplifiers
- A transistor amplifier in common emitter configuration has a current gain (β) that depends on the load impedance, hfe, and hoe.
- For a load impedance of 1 kΩ, hfe = 50, and hoe = 25 μΑ/V, the current gain is -48.78.
- The output voltage of a common emitter configuration amplifier using an NPN transistor with β = 100 is dependent on the circuit configuration.
Semiconductor Properties
- The concentration of electrons and holes in a semiconductor affects its properties, with a concentration of 8 × 1018/m3 electrons and 5 × 1018/m3 holes resulting in a specific semiconductor type and resistivity.
- The mobilities of electrons and holes, 2.3 m2/volt-sec and 0.01 m2/volt-sec respectively, also influence the semiconductor's properties.
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Description
Multiple choice questions on semiconductor physics, including p-type semiconductors, light required to create a hole, and diode circuits.
