$useBTBT

Modeling the band to band tunneling (BTBT) with the BTBT formalism. The band to band tunneling rates are decided by
$G=a\times |E{|}^p\times exp(-\frac{b}{|E|})+a2\times |E{|}^{p2}\times exp(-\frac{b2}{|E|})$

The unit of b is mV/cm The unit of a is $c{m}^{-3}{s}^{-1}$

For example:

$useBTBT 
a b p a2 b2 p2 
a b p a2 b2 p2 
a b p a2 b2 p2 
a b p a2 b2 p2
...
...
... N layers

In each layer, you will need to set the a b p coefficients. If you don't want to consider BTBT in this layer. please set a and a2 equal to 0.0.