Provided is an organic light emitting display, in which a semiconductor circuit unit of 2T-1C structure including a switching transistor and a driving transistor formed of single crystalline silicon is formed on a plastic substrate. A method of fabricating the single crystalline silicon includes: growing a single crystalline silicon layer to a predetermined thickness on a crystal growth plate; depositing a buffer layer on the single crystalline silicon layer; forming a partition layer at a predetermined depth in the single crystalline silicon layer by, e.g., implanting hydrogen ions in the single crystalline silicon layer from an upper portion of an insulating layer; attaching a substrate to the buffer layer; and releasing the partition layer of the single crystalline silicon layer by heating the partition layer from the crystal growth plate to obtain a single crystalline silicon layer of a predetermined thickness on the substrate.