Metal-organic pulsed laser deposition for stoichiometric complex oxide thin films
Methods and systems for forming complex oxide films are provided. Also provided are complex oxide films and heterostructures made using the methods and electronic devices incorporating the complex oxide films and heterostructures. In the methods pulsed laser deposition is conducted in an atmosphere containing a metal-organic precursor to form highly stoichiometric complex oxides.
1. A method of forming a complex oxide film, the method comprising:
providing a deposition substrate and at least one metal oxide target comprising a first cation metal and oxygen in a deposition chamber;
introducing a metal-organic precursor comprising a second cation metal and oxygen into the deposition chamber; and
laser ablating the metal oxide target using a pulsed laser in the presence of the metal-organic precursor to generate a flux of the metal oxide, wherein the metal oxide and the metal and oxygen from the metal-organic precursor are sequentially deposited onto the deposition substrate to form a layered complex oxide film.
2. The method of claim 1 , wherein the deposition substrate has a different composition than the layered complex oxide film.
3. The method of claim 2 , wherein the layered complex oxide film is in a strained state.
4. The method of claim 1 , wherein the metal oxide target has the formula MO x , where M is the first cation metal and x is in the range from 1 to 2.
5. The method of claim 4 , wherein the metal oxide target is an SrO target, the second cation metal is titanium, and the complex oxide film is an SrTiO 3 film.
6. The method of claim 5 , wherein the metal-organic precursor comprises titanium tetraisopropoxide.
7. The method of claim 5 , further comprising growing an LaAlO 3 film on the SrTiO 3 film.
8. The method of claim 7 , wherein the deposition substrate is a DyScO 3 substrate or a GdScO 3 substrate, the SrTiO 3 film is tensilely strained, and a 2DEG is formed at the interface between the SrTiO 3 film and the LaAlO 3 film.
9. The method of claim 7 , wherein the deposition substrate is a (LaAlO 3 ) 0.3 —(Sr 2 AlTaO 6 ) 0.7 substrate or a NdGaO 3 substrate, the SrTiO 3 film is compressively strained, the LaAlO 3 film has a thickness of 9 unit cells or fewer, and a 2DEG is formed at the interface between the SrTiO 3 film and the LaAlO 3 film.
10. The method of claim 1 , wherein the metal oxide target has the formula M 1-x M″ x O, where M is the first cation metal, M″ is a third cation metal, and 0<x<1.
11. The method of claim 1 , further comprising depositing a second complex oxide film over the layered complex oxide film.
12. The method of claim 11 , wherein a 2DEG is formed at the interface between the second complex oxide film and the layered complex oxide film.