For a function F(z) to qualify as a CDF,

- The function must be monotonic: F(z) ≥ F(a) for all z>a
- The function must be zero at the low end of the range: F(z
_{min}) = 0
- The function must be one at the high end of the rangeL F(z
_{max}) = 1.

Given that, does your result look like a CDF?

A couple of hints:

1. Your limits of integration aren't right.

2. What values can z take on? Can it be a large negative number? A large positive number? Zero?