$useBTBT

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

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

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.