Tin based p-type oxide semiconductor and thin film transistor applications
This disclosure provides p-type metal oxide semiconductor thin films that display good thin film transistor (TFT) characteristics. The p-type metal oxide thin films include ternary or higher order tin-based (Sn-based) p-type oxides such as Sn (II)-M-O oxides where M is a metal. In some implementations, M is a metal selected from the d block or the p block of the periodic table. The oxides disclosed herein exhibit p-type conduction and wide bandgaps. Also provided are TFTs including channels that include p-type oxide semiconductors, and methods of fabrication. In some implementations, the p-channel TFTs have low off-currents.
1. An apparatus comprising a thin film transistor (TFT), the TFT comprising:
a source electrode;
a drain electrode; and
a semiconductor channel connecting the source electrode and the drain electrode, the semiconductor channel including a ternary or higher order tin-based (Sn-based) p-type oxide, wherein the ternary or higher order Sn-based p-type oxide comprises Sn (II).
2. The apparatus of claim 1 , wherein the ternary or higher order Sn-based p-type oxide comprises a metal selected from the d block or the p block of the periodic table.
3. The apparatus of claim 1 , wherein the ternary or higher order Sn-based p-type oxide comprises one or more metals selected from the group consisting of Group 3 metals, Group 4 metals, tungsten (W), boron (B), niobium (Nb), aluminum (Al), gallium (Ga), lead (Pb), and silicon (Si).
4. The apparatus of claim 1 , wherein the Sn-based p-type oxide is a Sn-M-O ternary oxide, where Sn is Sn (II) and M is a metal selected from the d block or the p block of the periodic table.
5. The apparatus of claim 4 , wherein the Sn-M-O ternary oxide has the formula SnxM1-xOz, wherein x is at least 0.2 and z is greater than zero.
6. The apparatus of claim 5 , wherein x is between 0.2 and 0.8.
7. The apparatus of claim 1 , wherein the Sn-based p-type oxide is Sn (II)xB1-xOz, where x is between 0.7 and 0.9 and z is greater than zero.
8. The apparatus of claim 1 , wherein Sn-based p-type oxide is selected from the group consisting of Sn (II)xW1-xOz, Sn (II)xTi1-xOz and Sn (II)xNb1-xOz, where x is between 0.3 and 0.8 and z is greater than zero.
9. The apparatus of claim 1 , wherein the Sn-based p-type oxide is amorphous.
10. The apparatus of claim 1 , wherein the Sn-based p-type oxide has contributions from the Sn 5s orbital in its valence band maximum (VBM).
11. The apparatus of claim 1 , wherein the TFT is part of a complementary metal-oxide-semiconductor (CMOS) TFT device.
12. The apparatus of claim 1 , wherein the TFT is a bottom gate TFT.
13. The apparatus of claim 1 , wherein the TFT is a top gate TFT.
14. The apparatus of claim 1 , further comprising:
a display;
a processor that is configured to communicate with the display, the processor being configured to process image data; and
a memory device that is configured to communicate with the processor.
15. The apparatus of claim 14 , further comprising:
a driver circuit configured to send at least one signal to the display; and
a controller configured to send at least a portion of the image data to the driver circuit.
16. The apparatus of claim 15 , wherein the driver circuit includes the TFT.
17. The apparatus of claim 14 , further comprising:
an image source module configured to send the image data to the processor, wherein the image source module includes at least one of a receiver, transceiver, and transmitter.
18. The apparatus of claim 14 , further comprising:
an input device configured to receive input data and to communicate the input data to the processor.
19. The apparatus of claim 1 , wherein the ternary or higher order Sn-based p-type oxide comprises one or more metals selected from the group consisting of tungsten (W), titanium (Ti), niobium (Nb), boron (B), lead (Pb), and silicon (Si).
20. An apparatus comprising a thin film transistor (TFT), the TFT comprising:
a source electrode;
a drain electrode; and a semiconductor channel connecting the source electrode and the drain electrode, the semiconductor channel including a ternary or higher order tin-based (Sn-based) p-type oxide, wherein the Sn-based p-type oxide is a Sn-M1-M2-O quaternary oxide, where Sn is Sn (II) and M1 and M2 are metals selected from the d block or the p block of the periodic table.
21. A method, comprising:
providing a substrate;
forming a ternary or higher order tin-based (Sn-based) p-type oxide semiconductor layer on the substrate, wherein the ternary or higher order Sn-based p-type oxide comprises Sn (II); and
annealing the Sn-based p-type oxide semiconductor layer.
22. The method of claim 21 , wherein the ternary or higher order Sn-based p-type oxide a metal selected from the d block or the p block of the periodic table.
23. The method of claim 21 , wherein the ternary or higher order Sn-based p-type oxide one or more metals selected from the group consisting of Group 3 metals, Group 4 metals, tungsten (W), boron (B), niobium (Nb), aluminum (Al), gallium (Ga), lead (Pb) and silicon (Si).
24. The method of claim 21 , wherein forming the Sn-based p-type oxide semiconductor layer comprises an atomic layer deposition (ALD) process.
25. The method of claim 21 , further comprising forming a gate electrode and a gate dielectric, wherein the gate dielectric is between the Sn-based p-type oxide semiconductor layer and the gate electrode.
26. An apparatus comprising a thin film transistor (TFT), the TFT comprising:
a source electrode;
a drain electrode; and
a semiconductor channel connecting the source electrode and the drain electrode, the semiconductor channel including a ternary or higher order tin-based (Sn-based) p-type oxide, wherein the Sn-based p-type oxide is a Sn-M-O ternary oxide, where Sn is Sn (II) and M is a metal selected from the d block or the p block of the periodic table and wherein the Sn-M-O ternary oxide has the formula SnxM 1-x Oz, wherein x is at least 0.2 and z is greater than zero.