Derivative of ${}_1F_1$ hypergeometric function with respect to $z$ raised to the power of $m$.

Question

Hi I am interested in finding the $n$th derivative of this function with respect to $z$. When I try in Mathematica the solution gives rise to two new hypergeometric functions and the solution gets more complex as I keep derivating.

$$ {}_1F_1 (a,b,z^m)$$

Thank so much in advance.