Finding the Saturation Current of a photodiode in Reverse Bias

In summary, Ronald is trying to find the saturation current for a PN photodiode using data from a previous investigation.
  • #1
r.macdonald
1
0

Homework Statement



I am trying to finish the equation, to compare it against a set of data so I can then find the accuracy of my results in relation to the equation:

I(dark) = I(sat) * e(qV/kT) -1

I have the following data:
Va - the applied (bias) voltage
q
kB - Boltzmann Constant
T the absolute temperature.


Homework Equations



as above

The Attempt at a Solution



As the operating temperature of the photodiode increases, two distinctive changes occur in the operating characteristics. The first change is a shift in the Quantum Efficiency due to changes in the radiation absorption of the device. The efficiency decreases in the UV region, while it increases in the IR region, over an increasing operating temperature, effectively making the photodiode more sensitive in the IR region.
The second change, which this investigation highlights, is an exponential increase in dark current, since the electron-hole pairs become excited.

However, to compare the results of this investigation to the equation, I need to obviously know the saturation current of the photodiode. I am using a PN photodiode, so do these types of photodiodes all have a similar saturation current?

Ronald.
 
Physics news on Phys.org
  • #2
Welcome to the PF. A couple quick clarifications:

-- remember the parenthesis in your equation: I(dark) = I(sat) * [ e(qV/kT) -1 ]

-- and I believe you mean PIN photodiode, not PN photodiode, correct?

Now, I would think you should be able to find the Isat on the datasheet for your PIN photodiode. Do you have the part number of the diode, or the datasheet already?
 
  • #3
I did a quick google search for pin photodiode Isat datasheet, but didn't get any good sites. Then I used Digikey.com to find a common vendor of PIN photodiodes, and here is a page from them that lists a number of photodetector datasheets near the bottom of the page:

http://www.i-fiberoptics.com/Fiber_optic_led_photodetectors.php
 

FAQ: Finding the Saturation Current of a photodiode in Reverse Bias

1. What is the purpose of finding the saturation current of a photodiode in reverse bias?

The saturation current is an important characteristic of a photodiode as it indicates the maximum current that can flow through the device when it is reverse biased. This information is useful in understanding the behavior of the photodiode and in designing circuits that use it.

2. How is the saturation current measured?

The saturation current is typically measured by applying a reverse bias voltage to the photodiode and measuring the resulting current. The reverse bias voltage is gradually increased until the current reaches a constant value, which is the saturation current.

3. What factors can affect the saturation current of a photodiode?

The saturation current of a photodiode can be affected by factors such as temperature, light intensity, and the materials used in the device. Higher temperatures and light intensity can increase the saturation current, while using materials with lower bandgap energies can decrease it.

4. How does the saturation current relate to the dark current of a photodiode?

The saturation current is a component of the dark current, which is the current that flows through a photodiode when it is not exposed to light. The dark current also includes other components such as leakage current, which can affect the overall performance of the photodiode.

5. Can the saturation current of a photodiode change over time?

Yes, the saturation current of a photodiode can change over time due to factors such as aging, temperature, and external stress. It is important to regularly measure the saturation current to ensure the photodiode is functioning properly and to make any necessary adjustments in circuit design.

Back
Top