Finding reverse sat current of pn junction diode

In summary, to determine the reverse saturation current of a diode, you will need to use the ideal diode current density formula for an abrupt pn junction diode. However, if you are only given or shown the i-v for positive values, between 0 and 0.8V, you will not be able to directly observe the reverse saturation current. You will need to consider using a general equation for a diode's i-v characteristic.
  • #1
ralph13
1
0

Homework Statement


Determine reverse sat current of diode. To show and explain approach. Given-IV characteristics of diode and tabulated values for forward bias voltage from 0-0.8v and corresponding current values.


Homework Equations


At which point do I need to consider to find the reverse sat current


The Attempt at a Solution


using formula of ideal diode current densityfor an abrupt pn junction diode??
 
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  • #2
it's been a while since I've done diode problems... but from the IV characteristics graph, can't you determine the reverse sat current from the graph? not sure if forward bias voltages help, because you need the diode to be reverse biased (V < 0V) to see reverse sat current... did that help? or maybe I'm just not understanding your question..
 
  • #3
Welcome to PF, ralph13.

If you are only given or shown the i-v for positive values, between 0 and 0.8V, that rules out a direct observation.

Do you have a general equation for a diode's i-v characteristic?
 

1. How does a pn junction diode work?

A pn junction diode is made up of two layers of semiconductor materials, one with an excess of negative charge carriers (n-type) and one with an excess of positive charge carriers (p-type). When the two layers are joined together, the excess charge carriers diffuse across the junction, creating a depletion zone. When a forward voltage is applied, the depletion zone becomes smaller, allowing current to flow through the diode. In reverse bias, the depletion zone widens, preventing current from flowing.

2. What is the reverse saturation current of a pn junction diode?

The reverse saturation current, also known as the reverse leakage current, is the small amount of current that flows through a pn junction diode in reverse bias. This current is due to the diffusion of minority carriers across the junction and is typically very small, on the order of nanoamperes or even less.

3. Why is it important to find the reverse saturation current of a pn junction diode?

The reverse saturation current is a critical parameter for understanding the behavior of a pn junction diode. It can affect the efficiency and performance of electronic devices that use diodes, such as transistors and solar cells. Additionally, knowing the reverse saturation current can help in troubleshooting and diagnosing issues with diode circuits.

4. How can the reverse saturation current of a pn junction diode be measured?

The reverse saturation current can be measured using a multimeter in diode test mode. The diode should be placed in reverse bias and the current reading can be taken. However, this method may not be accurate for very small currents. In this case, specialized equipment such as a semiconductor parameter analyzer may be used.

5. What factors can affect the reverse saturation current of a pn junction diode?

The reverse saturation current can be affected by temperature, as an increase in temperature can increase the number of minority carriers and thus increase the reverse leakage current. The doping concentration of the diode also plays a role, as a higher doping concentration can result in a higher reverse saturation current. Additionally, any defects or impurities in the diode can also impact the reverse leakage current.

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