Stable P-type semiconducting behaviour in Li and Ni codoped ZnO
View Patent ↗A method is provided for growing a stable p-type ZnO thin film with low resistivity and high mobility. The method includes providing an n-type Li—Ni co-doped ZnO target in a chamber, providing a substrate in the chamber, and ablating the target to form the thin film on the substrate.
1. A stable p-type lithium (Li) and a transition metal codoped zinc oxide (ZnO) thin film comprising, at room temperature, a resistivity selected from a range of about 0.01 to 1 Ωcm, a hole concentration selected from a range of about 10 17 cm −3 to 10 18 cm −3 , and a mobility selected from a range of about 80 to 250 cm 2 V −1 s −1 , the hole concentration remaining within ±20% of an initial value for about 100 days after the p-type Li and the transition metal codoped ZnO thin film is deposited.
2. The thin film of claim 1 , wherein the transition metal is nickel (Ni).
3. The thin film of claim 1 , wherein the resistivity is about 0.15 Ωcm, the hole concentration is about 3.2*10 17 cm −3 , and the mobility is about 130 cm 2 V −1 s −1 .
4. A device, comprising:
a substrate;
a zinc oxide (ZnO) buffer layer;
an n-type ZnO layer over the ZnO buffer layer;
a p-type lithium (Li) and a transition metal codoped ZnO layer over the n-type ZnO layer, the p-type Li and the transition metal codoped ZnO layer comprising, at room temperature, a resistivity selected from a range of about 0.01 to 1 Ωcm, a hole concentration selected from a range of about 10 17 cm −3 to 10 18 cm −3 , and a mobility selected from a range of about 80 to 250 cm 2 V −1 s −1 , the hole concentration remaining within ±20% of an initial value for about 100 days after the p-type Li and the transition metal codoped ZnO thin film is deposited;
a first electrode coupled to the n-type ZnO layer; and
a second electrode coupled to the p-type ZnO layer.
5. The device of claim 4 , wherein the transition metal is nickel (Ni).
6. The device of claim 5 , wherein the resistivity is about 0.15 Ωcm, the hole concentration is about 3.2*10 17 cm −3 , and the mobility is about 130 cm 2 V −1 s −1 .
7. The device of claim 4 , wherein the substrate is sapphire.
8. The device of claim 4 , wherein the p-type Li and the transition metal codoped ZnO layer has a thickness of about 500 nm.
9. The device of claim 4 , wherein the ZnO buffer layer has a thickness of about 100 nm.
10. The device of claim 4 , wherein the n-type ZnO layer comprises a Al doped ZnO layer.
11. The device of claim 10 , wherein the Al doped ZnO layer comprises about two mol % of Al.
12. The device of claim 10 , wherein the Al doped ZnO layer has a thickness of about 500 nm.
13. The device of claim 4 , wherein the device is a light-emitting diode.
14. A device, comprising:
a substrate; and
a p-type lithium (Li) and a transition metal codoped zinc oxide (ZnO) layer over the substrate, the p-type Li and the transition metal codoped ZnO layer comprising, at room temperature, a resistivity selected from a range of about 0.01 to 1 Ωcm, a hole concentration selected from a range of about 10 17 cm −3 to 10 18 cm −3 , and a mobility selected from a range of about 80 to 250 cm 2 V −1 s −1 , the hole concentration remaining within ±20% of an initial value for about 100 days after the p-type Li and the transition metal codoped ZnO layer is deposited.
15. The device of claim 14 , further comprising:
a buffer layer over the substrate.
16. The device of claim 15 , wherein the buffer layer comprises an undoped intrinsic ZnO layer.
17. The device of claim 14 , further comprising:
an n-type layer over the buffer layer.
18. The device of claim 17 , wherein the n-type layer comprises an aluminum (Al) doped ZnO layer.
19. The device of claim 17 , wherein the p-type Li and the transition metal codoped ZnO layer is formed atop the n-type layer to form a homojunction.
20. The device of claim 14 , wherein the device is a light-emitting device.