Podcast
Questions and Answers
What happens to the potential barrier when a PN junction diode is in reverse bias?
What happens to the potential barrier when a PN junction diode is in reverse bias?
- Establishes an equilibrium
- Increases the potential barrier (correct)
- Decreases the potential barrier
- Eliminates the potential barrier
In a zero-biased junction diode, which term describes the flow of majority carriers across the junction?
In a zero-biased junction diode, which term describes the flow of majority carriers across the junction?
- Reverse Current
- Forward Current (correct)
- Drift Current
- Dynamic Equilibrium
What is established when majority carriers are equal and moving in opposite directions in a PN junction diode?
What is established when majority carriers are equal and moving in opposite directions in a PN junction diode?
- Dynamic Equilibrium (correct)
- Static State
- Forward Bias Condition
- Reverse Bias Condition
Which type of current flows due to thermal energy in a zero-biased PN junction?
Which type of current flows due to thermal energy in a zero-biased PN junction?
What is the result of increasing the temperature of a zero-biased PN junction?
What is the result of increasing the temperature of a zero-biased PN junction?
In a PN junction diode, which carriers move across the junction in reverse bias conditions?
In a PN junction diode, which carriers move across the junction in reverse bias conditions?
Which condition describes a scenario with no external potential applied to a PN junction?
Which condition describes a scenario with no external potential applied to a PN junction?
What occurs to the net current in a zero-biased PN junction when dynamic equilibrium is reached?
What occurs to the net current in a zero-biased PN junction when dynamic equilibrium is reached?
What happens to the depletion layer of a junction diode when a forward biasing voltage is applied?
What happens to the depletion layer of a junction diode when a forward biasing voltage is applied?
At which point on the I-V characteristics curve does the sudden increase in current take place for a junction diode?
At which point on the I-V characteristics curve does the sudden increase in current take place for a junction diode?
Why are resistors used in series with a diode?
Why are resistors used in series with a diode?
What is the potential difference across a silicon junction diode when it is conducting?
What is the potential difference across a silicon junction diode when it is conducting?
What describes the PN junction region of a junction diode?
What describes the PN junction region of a junction diode?
What occurs if the maximum forward current specification of a diode is exceeded?
What occurs if the maximum forward current specification of a diode is exceeded?
What effect does a negative voltage have on the electrons in a junction diode?
What effect does a negative voltage have on the electrons in a junction diode?
What is the primary characteristic of a forward-biased junction diode?
What is the primary characteristic of a forward-biased junction diode?
What happens to the depletion layer when a diode is in reverse bias?
What happens to the depletion layer when a diode is in reverse bias?
What is the primary effect of applying a high reverse bias voltage to a diode?
What is the primary effect of applying a high reverse bias voltage to a diode?
What is the typical magnitude of reverse leakage current in a reverse-biased diode?
What is the typical magnitude of reverse leakage current in a reverse-biased diode?
In a forward biased diode, what must the external voltage exceed to allow current to flow?
In a forward biased diode, what must the external voltage exceed to allow current to flow?
What characteristic does a reverse-biased diode primarily exhibit?
What characteristic does a reverse-biased diode primarily exhibit?
What is a Zener diode commonly used for in electronic circuits?
What is a Zener diode commonly used for in electronic circuits?
Which statement regarding the diode's characteristics curve in reverse bias is correct?
Which statement regarding the diode's characteristics curve in reverse bias is correct?
Why is the depletion layer important in reverse-biased diodes?
Why is the depletion layer important in reverse-biased diodes?
What occurs when a suitable positive voltage is applied to a PN junction diode?
What occurs when a suitable positive voltage is applied to a PN junction diode?
What characterizes the current-voltage relationship in a PN junction diode?
What characterizes the current-voltage relationship in a PN junction diode?
What happens to the depletion layer width when a negative voltage is applied to a PN junction diode?
What happens to the depletion layer width when a negative voltage is applied to a PN junction diode?
Which statement accurately describes rectification in a PN junction diode?
Which statement accurately describes rectification in a PN junction diode?
What forms the potential barrier voltage across a PN junction diode?
What forms the potential barrier voltage across a PN junction diode?
What effect does forward bias have on a PN junction diode?
What effect does forward bias have on a PN junction diode?
Which component is NOT part of a PN junction diode?
Which component is NOT part of a PN junction diode?
What is a consequence of the asymmetric conducting property of a PN junction diode?
What is a consequence of the asymmetric conducting property of a PN junction diode?
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Study Notes
PN Junction Diode
- A PN junction diode is formed when a p-type semiconductor is fused to an n-type semiconductor creating a potential barrier voltage across the diode junction
- Adding an external energy source (battery) can overcome the potential barrier
- Free electrons can then cross the depletion region due to the external energy source
- This creates a two-terminal device known as the PN Junction Diode
- A PN Junction Diode passes current in one direction only
- The diode does not behave linearly with respect to the applied voltage due to an exponential current-voltage relationship
- Forward bias decreases the width of the depletion layer around the PN junction
- Reverse bias increases the width of the depletion layer around the PN junction
- This results in the diode acting as a rectifier
Biasing Conditions
- Zero Biased: No external potential energy is applied. Majority carriers move across the junction resulting in "forward current" and "reverse current"
- Forward Biased: A negative voltage on the N-type material and a positive voltage on the P-type material overcome the potential barrier and current starts to flow
- Reverse Biased: A positive voltage on the N-type material and a negative voltage on the P-type material creates a high impedance path and prevents current flow (except for a small reverse leakage current)
Depletion Layer
- Forward Bias: Depletion Layer width reduces, allowing high currents to flow
- Reverse Bias: Depletion Layer width increases, blocking current flow
Diode Characteristics
- Forward Characteristics Curve: Shows a "knee" point where current rapidly increases with a small increase in voltage (due to overcoming the potential barrier)
- Reverse Characteristics Curve: Shows very little current flow until a high reverse voltage is applied, causing the avalanche effect and diode failure
- Static I-V Characteristics: Demonstrate diode current-voltage behavior and are polarity dependent
Practical Considerations
- Resistors: Used in series with the diode to limit current flow to prevent damage due to exceeding maximum forward current rating
- Zener Diodes: Used for voltage stabilization by utilizing the avalanche effect at a specific reverse voltage
Key Facts
- Silicon Diodes: Have a potential barrier of ~0.7 volts
- Germanium Diodes: Have a potential barrier of ~0.3 volts
- Avalanche Effect: Occurs in reverse bias, a high voltage causes the diode to overheat and fail
- Rectification: Allows current to flow in one direction, blocking flow in the other, enabling AC to DC conversion
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