Organic light emitting diode display apparatus

A method of fabricating an organic light emitting display apparatus, the method comprising:

• providing a substrate including a first portion and a second portion that is spaced apart from the first portion;
• forming a lower buffer layer on the substrate;
• forming a polycrystalline semiconductor layer on the lower buffer layer;
• planarizing an upper surface of a first portion of the polycrystalline semiconductor layer that is on the first portion without planarizing an upper surface of a second portion of the polycrystalline semiconductor layer that is on the second portion of the substrate;
• forming a first polycrystalline semiconductor pattern in the first portion and a first plurality of protrusions at the upper surface of the lower buffer layer in the second portion by etching the polycrystalline semiconductor layer;
• and
• forming a first oxide semiconductor pattern over the first plurality of protrusions, the first oxide semiconductor pattern including a second plurality of protrusions that overlap the first plurality of protrusions.

A display device comprising:

• a substrate including a display area and a non-display area;
• a first transistor in the display area, the first transistor including a first semiconductor layer with a first plurality of protrusions on at least a portion of a surface of the first semiconductor layer;
• a second transistor in the non-display area, the second transistor including a second semiconductor layer that is made of a different material than the first semiconductor layer and a surface of the second semiconductor layer is planarized;
• and
• a light emitting device in the display area, the light emitting device electrically connected to the first transistor.