|To make a RAID array of any kind you need at least two hard disks.|
Having said that I would avoid RAID 0 like the plague. it will do nothing for you and make data recovery impossible in the event of one disk failing. That can be either a hardware failure or a software failure.
Read this to find out exactly what RAID is and if you really need it. The chances are you don't and any RAID is just an unnecessary complication.