How does an IV curve of a bulk semiconductor look like?
A bulk semiconductor behaves like a resistor, with the current directly proportional to the applied voltage.

The value of the resistance depends on the band gap of the material in question and its temperature, which determines the number of charge carriers (electrons or holes) that are in the conduction band. Higher band gaps and/or lower temperatures mean that fewer charge carriers are free to move, making the resistance higher &mdash; in some cases, high enough to be considered an insulator.

Doping (of either type) can make more charge carriers available, reducing the resistance as compared to undoped (intrinsic) material.