Raid-0 (Max performance for 2 drives, also relatively cheap) needs at least 2 drives. Raid-0 splits the data between the drives. If one drive fails all your data is now unrecoverable, even if the other drive(s) are still working.
Raid-1 (Max reliabilty) is a 1:1 thing, 1 hard disk, 1 backup.
Raid 0+1 (A balance of reliability and performance, though cost is an issue) is a setup that needs 4 drives, two pairs of Raid-0, wherein the secondary Raid-0 would function as like the backup drive on a Raid-1 setup.
Raid-5 (Max performance, though you'd need an expensive controller for this) needs at least 4 drives if you don't want the redundancy, put in the 5th if you need redundancy.
Raid-6 is a raid 5 with 2 redundant drives instead of 1.
You could just JBOD the three (Just-a-Bunch-Of-Drives) though the performance increase is not guranteed. Though JBOD is just like Raid-0, if one drive fails, all you can do is reformat them all.