Field-effect transistor and method for manufacturing the same
A method for manufacturing a field-effect transistor includes the steps of forming a source electrode and a drain electrode each containing hydrogen or deuterium; forming an oxide semiconductor layer in which the electrical resistance is decreased if hydrogen or deuterium is added; and, causing hydrogen or deuterium to diffuse from the source electrode and the drain electrode to the oxide semiconductor layer.
1. A method for manufacturing a field-effect transistor, comprising the steps of:
forming a source electrode and a drain electrode each containing hydrogen or deuterium;
forming an oxide semiconductor layer, the electrical resistance of the oxide semiconductor layer being decreased if hydrogen or deuterium is added; and
causing hydrogen or deuterium to diffuse from the source electrode and the drain electrode to the oxide semiconductor layer.
2. The method for manufacturing a field-effect transistor according to claim 1 , wherein the step of forming a source electrode and a drain electrode each containing hydrogen or deuterium is a step of forming the source electrode and the drain electrode in an atmosphere containing an H 2 gas, a step of forming the source electrode and the drain electrode in an atmosphere containing an H 2 O gas, a step of (a) treating the source electrode and the drain electrode with hydrogen plasma after the formation of the source electrode and the drain electrode, or (b) bombarding the source electrode and the drain electrode with accelerated hydrogen ions after the formation of the source electrode and the drain electrode.
3. The method for manufacturing a field-effect transistor according to claim 1 , wherein the concentration of hydrogen ions diffused in the step of causing hydrogen or deuterium to diffuse from the source electrode and the drain electrode to the oxide semiconductor layer is in the range of 0.1 to 10 atomic percent in regions in the oxide semiconductor layer in contact with the source electrode and the drain electrode.
4. The method for manufacturing a field-effect transistor according to claim 1 , wherein the concentration of hydrogen ions diffused in the step of causing hydrogen or deuterium to diffuse from the source electrode and the drain electrode to the oxide semiconductor layer is in the range of 0.5 to 5 atomic percent in regions in the oxide semiconductor layer in contact with the source electrode and the drain electrode.
5. The method for manufacturing a field-effect transistor according to claim 1 , wherein the step of causing hydrogen or deuterium to diffuse from the source electrode and the drain electrode to the oxide semiconductor layer is an annealing step.
6. The method for manufacturing a field-effect transistor according to claim 1 , wherein the oxide semiconductor layer is formed of an amorphous oxide material containing In, Ga, and Zn.
7. A field-effect transistor comprising:
an oxide semiconductor layer, the electrical resistance of the oxide semiconductor layer being decreased if hydrogen or deuterium is added,
wherein the concentration of hydrogen or deuterium in regions in the oxide semiconductor layer in contact with a source electrode and a drain electrode is higher than the average concentration of hydrogen or deuterium in the oxide semiconductor layer.
8. The field-effect transistor according to claim 7 , wherein the hydrogen-ion concentration of the regions in the oxide semiconductor layer in contact with the source electrode and the drain electrode is in the range of 0.1 to 10 atomic percent.
9. The field-effect transistor according to claim 7 , wherein the hydrogen-ion concentration of the regions in the oxide semiconductor layer in contact with the source electrode and the drain electrode is in the range of 0.5 to 5 atomic percent.
10. The field-effect transistor according to claim 7 , wherein the oxide semiconductor layer is formed of an amorphous oxide material containing In, Ga, and Zn.
11. A display apparatus comprising display devices, and having a field-effect transistor according to claim 7 , wherein electrodes of each of the display devices are electrically connected to the source electrode or the drain electrode of the field-effect transistor.
12. The display apparatus according to claim 11 , wherein the display devices are electroluminescent devices.
13. The display apparatus according to claim 11 , wherein the display devices are liquid crystal cells.
14. The display apparatus according to claim 11 , wherein a plurality of display devices and a plurality of field-effect transistors are two-dimensionally arranged on a substrate.