I want to find electron lifetime from the open circuit voltage decay measurement using equation.
The equation is: Electron life time= -[(KBT)/e]*(dVoc/dt)^(-1)
where KB is the Boltzmann constant, T is the absolute temperature, e is the positive elementary charge, and t is the time interval of the OCVD measurement.
Below I have attached the Voc values. How to convert from Voc values to life time?
You only attached the values for Voc but without a time line. What you can do pretty easily is to plot Voc in dependence of time, so Voc(t). Then derive this curve with respect to t. That gives you dVoc/dt (which should be a constant value for a linear voltage decay) and then you just insert that into your equation.
The open circuit voltage decay with time is a conventional method to measure the life time of the minority carriers in the base of the pn junction diodes.
It is so that the stored charges decay exponentially with time because of recombination.
It is so the excess charges decay exponentially with time such that
delta p = delta p(0) exp -t/ Tau , where Tau is the lifetime and delta p (0) is the intial excess hole concentration at zero time, the instant of interrupting the diode current after forward bias.
On the other side according to the law OF THE JUNCTION:
delta p = Pno exp V/ Vt, where Pno is the minority carrier concatenation at thermal equilibrium and Vt the thermal voltage.,
equating both equations one gets:
V/Vt= V(0)/Vt - t/Tau,
Differentiating the above relation, we get finally;
delta V/ delta t = Vt / Tau.,
If the diode has an ideality factor n, one has to modify the above equation to:
delta V/ delta t = n Vt / Tau.,
To get the lifetime you have to display V(t) as a function of time and evaluate the slope of the curve at the larger values V where the effect of the space chrge junction capacitance is negligible. This has been noticed by Johannes.
wish you success.
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