# how to calculate recombination lifetime for holes for a specific diode?

I need to calculate $\tau_p$ (recombination lifetime for holes) for a specific diode (1N4004).

We were able to do it with an experiment using the following equation:

$$t_{sd} = \tau_p\ln\left(1 + \frac{I_f}{I_r}\right)$$

where $\tau_p$ was isolated. This is for a laboratory. We are not asked to find the real value, but out of curiosity I'd like to know the validity of our results. I have the datasheet of the diode, but I can't find the real value of $\tau_p$.

Is there a way to calculate it from values in the datasheet, or to find it on the internet?

Constants list:

## 1 Answer

Correct me if I am wrong but wouldn't calculating $t_p$ use the following symbolic rearrangement?

$$t_p = \frac{t_{sd}}{\ln\left(1+ \frac{\text{Final forward current}}{\text{generator reverse current}}\right)}$$

(I can't read your picture very well so I could actually be REALLY wrong)

If that is the equation then that would lead me to conclude that it would depend on the specific circuit setup each time? Due to the fact that the natural log number would actually change. This would mean there is no "standard data sheet number" to compare to?

That and the data sheet wasnt very helpful (http://www.diodes.com/_files/datasheets/ds28002.pdf)