Calculate Bandgap Voltage for GaAs Photodiode: 5V Reverse Bias

[Infidel22]

Hello, I am having a bit of trouble with the following problem:

Assuming a built in voltage equal to the bandgap voltage, calculate the slowest possible transmit time for a carrier with 5V reverse bias applied to the GaAs photodiode.

I would be able to do this problem without difficulty if it wasnt for the part mentioning "Bandgap Voltage." I am familiar with bangap energy and how to calculate it, but I have no idea how to figure out the bandgap voltage for a given material. Can anyone give me any hints on this?

Thanks!

 

[Gokul43201]

convert bandgap energy to electron volts (if strangely, it isn't already in eV). The bandgap voltatge is numerically the same as this number.

 

[ravenprp]

To calculate the bandgap voltage for GaAs, you will need to know the bandgap energy of GaAs. This information can be found in a materials database or by referring to a materials science textbook. The bandgap energy for GaAs is approximately 1.43 eV (electron volts).

Once you have the bandgap energy, you can use the following formula to calculate the bandgap voltage:

Bandgap voltage = bandgap energy / electron charge

In this case, the electron charge is a constant value of 1.6 x 10^-19 Coulombs.

So for GaAs, the bandgap voltage would be:

Bandgap voltage = 1.43 eV / (1.6 x 10^-19 C) = 8.94 x 10^-15 V

Now that you have the bandgap voltage, you can use it to calculate the slowest possible transmit time for a carrier with 5V reverse bias applied to the GaAs photodiode.

The formula for this would be:

Transmit time = (2 x Bandgap voltage) / applied voltage

So for a 5V reverse bias, the transmit time would be:

Transmit time = (2 x 8.94 x 10^-15 V) / 5 V = 3.58 x 10^-15 seconds

I hope this helps you with the problem. Remember to always check your units and use the correct constants in your calculations. Good luck!