Make your own.

Define the current source transfer function as i=xyz*exp(abc)+exp(pqr) or whatever.

Dear Sandeep Gajendra,

A double exponential function is an exponential function whose exponent is itself an exponential function. This function grows faster than a simple exponential.

Also i suggest you to see links and attached file on subject.

https://link.springer.com/chapter/10.1007/978-3-319-30607-0_1

https://personal.utdallas.edu/~xxx110230/hspice/

Conference Paper Estimation Technique for SET-tolerance of Combinational ICs

Article Modeling of Single Event Transients With Dual Double-Exponen...

Best regards

So change the transfer function to i=exp(exp(abc)). SPICE can handle it.

Thank you Mohamed-Mourad Lafifi sir and Mark Sitkowski sir.

Dear Dr. Sandeep,

You can use synthesized current source, e.g., the sum of two (parallel) exponential current sources, one rising and the second is falling.

Good luck,

In addition to my previous solution to synthesize a double exponential source, you can can make a piecewise polynomial which yields the waveform of a double exponential current source (with initial fast rise, sharp peak and finally slow decay)

Dear sir:

You could benefit from this valuable article about your topic at:

https://www.analog.com/en/technical-articles/ltspice-using-time-dependent-exponential-sources-to-model-transients.html.

I hope it will be helpful...