Light emitting device and method of manufacturing the same

A method of manufacturing a light emitting device, comprising:

• forming a circuit tier on a substrate, the circuit tier comprising a transistor, wherein the substrate comprises a base material and a buffer layer over the base material, and forming the transistor comprises:
• forming an active layer over the buffer layer;
• forming a gate over the active layer;
• and
• forming source/drain regions on portions of the active layer on opposite sides of the gate, and forming a channel between the source/drain regions,
• wherein the active layer is produced with a flat upper surface through a planarization process;
• and
• forming a light emitting pixel over the circuit tier, and the light emitting pixel comprising a light emitting material.

A light emitting device, comprising:

• a substrate comprising a base material and a buffer layer over the base material;
• a circuit tier on the substrate, the circuit tier comprising a transistor, the transistor comprising:
• an active layer over the buffer layer;
• a gate over the active layer;
• and
• source/drain regions located at the active layer and on opposite sides of the gate, with a channel below the gate and between the source/drain regions,
• wherein the buffer layer comprises a planarized upper surface, and the planarized upper surface has a surface roughness Ra of less than at least 5nm;
• and
• a light emitting pixel over the circuit tier, and the light emitting pixel comprising a light emitting material.