Display device having a pixel including semiconductor layers having different semiconductor materials
A display device having an improved display characteristics and reduced manufacturing cost is provided. The display device includes a plurality of pixels arranged on a surface of a substrate. The plurality of pixels each include: a light-emitting element; a driving transistor; a selecting transistor; and a retention capacitor. The driving transistor has a bottom-gate structure. The driving transistor has a semiconductor layer containing a first semiconductor. The retention capacitor has a first electrode and a second electrode. The first electrode doubles as a gate of the driving transistor. The second electrode is disposed at a lower layer than the first electrode and contains a second semiconductor.
1. A display device including a plurality of pixels arranged on a surface of a substrate, each of the plurality of pixels comprising:
a light-emitting element;
a driving transistor;
a selecting transistor; and
a retention capacitor, wherein
the driving transistor has a bottom-gate structure, and includes a semiconductor layer containing a first semiconductor material,
the selecting transistor includes a semiconductor layer containing a second semiconductor material different from the first semiconductor material,
the retention capacitor has a first electrode and a second electrode,
the first electrode doubles as a gate of the driving transistor,
the second electrode is disposed at a lower layer than the first electrode with an insulating layer interposed therebetween and contains the second semiconductor material, and
the selecting transistor has a gate disposed at the same layer as the gate of the driving transistor.
2. The display device according to claim 1 , wherein the second semiconductor material has higher carrier mobility than the first semiconductor.
3. The display device according to claim 1 , wherein the selecting transistor has a top-gate structure and includes a semiconductor layer disposed at the same level as the second electrode.
4. The display device according to claim 1 , further comprising a peripheral circuit disposed on the surface of the substrate, the peripheral circuit including a plurality of transistors having the second semiconductor material and controlling light emission of the plurality of pixels.
5. The display device according to claim 1 , each of the plurality of pixels further comprising:
a first contact electrode provided in a first contact hole and connected to a source electrode of the driving transistor, the first contact hole extending from a higher layer than the driving transistor to the source electrode of the driving transistor; and
a second contact electrode provided in a second contact hole and connected to a drain of the driving transistor and the second electrode, the second contact hole extending from a higher layer than the driving transistor to the second electrode.
6. The display device according to claim 1 , wherein the selecting transistor has a source electrode disposed at the same layer as the source electrode of the driving transistor.
7. The display device according to claim 1 , wherein the first semiconductor material is an oxide semiconductor, and the second semiconductor material is polycrystalline silicon.