Method and apparatus for chemical deposition
View Patent ↗Embodiments of the present system and method are useful for chemical deposition, particularly continuous deposition of thin films. Disclosed systems typically comprise a micromixer and a microchannel applicator. A deposition material or materials is applied to a substrate, such as an oxidized silicon substrate, a flexible substrate useful for forming flexible devices, such as flexible transistors, and combinations of different substrates. Uniform and highly oriented surface morphologies of films deposited using disclosed embodiments are clearly improved compared to films deposited by a conventional batch process. The process can be used to tailor the composition and morphology of the material deposited on a substrate. The present process can be used at low temperatures as a post-deposition, high-temperature annealing step is obviated.
1. A process for forming a film on a substrate by chemical deposition, comprising: providing a first reactant; providing at least a second reactant;
flowing the first and second reactants to a micromixer to mix the first and second reactants to form a mixture; heating the mixture for a period of time sufficient to form reaction flux useful for forming a chemical deposition material capable of reacting with a substrate surface; controlling residence time of the mixture in the micromixer to substantially avoid produce a substantially particle-free flux formation;
heating a substrate to a temperature less than 90° C. to provide a heated substrate; and
depositing the deposition material substantially continuously on the heated substrate using a microchannel applicator without an intermediate isolation step and prior to substantial formation of particles, where the continuously flowing solution removes byproduct formed by mixing the reactants; and allowing the deposition material to form a device-quality continuous film on the substrate by a chemical deposition process without heating to a temperature required for annealing, where the first and second reactants are selected to form Au, Ag, Cu, Co, Cr, Ge, Ni, Pt, Pd, Rh, Se, Si, Ru, Ag2S, Ag2Se, AgO, Ag2O, Al2O3, As2S3, BaO, Bi2S3, Bi2Se3, CdO, CdS, CdSe, CdSnO, CdTe, CdZnS, CeO2, CoS, CoSe, CoO, CrO2, CuBiS2, CuGaSe2, Cu(In,Ga)Se2, CuInSe2, CuInS2, Cu2.xS, Cu2, xSe, Cu20, FeO(OH), Fe203, Fe304, GaAs, GaN, Ga203, GaP, Ge, GeO2, HfO2, HgS, HgSe, InGaAs, InAs, In203, InP, In253, In2Se3, La203, MgO, MnS, MnO2, M002, MoS2, MoSe2, NbO2, NiS, NiSe, NiO, PbHgS, PbS, PbSe, PbTe, PbO2, ReO3, RhO2, RuO2, Sb2S3, Sb2Se3, SiGe, SiO2, SnS, SnS2, SnSe, SnO2, Sb2S3, TiO2, T1S, T1Se, T1203, VO2, WO2, Y203, ZnO, ZnS, ZnSe, ZrO2, or combinations thereof.
2. The process according to claim 1 where the deposition material is CdS.
3. The process according to claim 2 where the first reactant comprises a cadmium halide.
4. The process according to claim 2 where the second reactant comprises thiourea.
5. The process according to claim 1 where the deposition material is CdS, ZnO, InO x or combinations thereof.
6. The process according to claim 1 where the first reactant, the second reactant, or both further comprise a complexing agent.
7. The process according to claim 6 where the complexing agent is a nitrogen-bearing compound.
8. The process according to claim 6 where the complexing agent is ammonia, an aliphatic amine, an aliphatic amide, or combinations thereof.
9. The process according to claim 6 where the complexing agent is ammonia, triethanolamine, ethanolamine, diethylenetriamine, ethylenediaminetetracetate, hydrazine, nitrilotriacetate, triethylenetriamine or combinations thereof.
10. The process according to claim 1 where the film is an epitaxial nanostructured film, a nanocrystalline film, an epitaxial film comprising embedded nanocrystals, a superlattice film, a composition gradient film, a composite film comprising core-shell nanoparticles, or combinations thereof.
11. The process according to claim 1 where the substrate is flexible.
12. The process according to claim 1 useful for making an electronic device, the process comprising forming an electronic device comprising the deposition material deposited on the substrate.
13. The process according to claim 12 where the device is a transistor.
14. The process according to claim 12 where the transistor is a flexible transistor.
15. The process according to claim 12 where the device is a solar cell, a flexible solar cell, a light emitting diode, a flexible light emitting diode, a detector, a flexible detector, a sensor, a flexible sensor, a switch or a flexible switch.
16. The process according to claim 13 where the transistor is a CdS MISFET.
17. The process according to claim 1 where the mixer is a micromixer.
18. The process according to claim 1 where the substrate is a rotating substrate, a roll-to-roll substrate, or a flow cell.
19. A method for forming an electronic device by a chemical deposition process, comprising:
providing at least a first reactant and at least a second reactant, where the first and second reactants are selected to form Au, Ag, Cu, Co, Cr, Ge, Ni, Pt, Pd, Rh, Se, Si, Ru, Ag 2 S, Ag 2 Se, AgO, Ag 2 O, Al 2 O 3 , As 2 S 3 , BaO, Bi 2 S 3 , Bi 2 Se 3 , CdO, CdS, CdSe, CdSnO, CdTe, CdZnS, CeO 2 , CoS, CoSe, CoO, CrO 2 , CuBiS 2 , CuGaSe 2 , Cu(In,Ga)Se 2 , CuInSe 2 , CuInS 2 , Cu 2-x S, Cu 2-x Se, Cu 2 O, FeO(OH), Fe 2 O 3 , Fe 3 O 4 , GaAs, GaN, Ga 2 O 3 , GaP, Ge, GeO 2 , HfO 2 , HgS, HgSe, InGaAs, InAs, In 2 O 3 , InP, In 2 S 3 , In 2 Se 3 , La 2 O 3 , MgO, MnS, MnO 2 , MoO 2 , MoS 2 , MoSe 2 , NbO 2 , NiS, NiSe, NiO, PbHgS, PbS, PbSe, PbTe, PbO 2 , ReO 3 , RhO 2 , RuO 2 , Sb 2 S 3 , Sb 2 Se 3 , SiGe, SiO 2 , SnS, SnS 2 , SnSe, SnO 2 , Sb 2 S 3 , TiO 2 , TlS, TlSe, Tl 2 O 3 , VO 2 , WO 2 , Y 2 O 3 , ZnO, ZnS, ZnSe, ZrO 2 , or combinations thereof;
flowing the first and second reactants to a micromixer to mix the first and second reactants to form a mixture;
heating the mixture for a period of time sufficient to form a reaction flux useful for forming a deposition material;
controlling residence time of the mixture in the micromixer to produce a substantially particle-free flux;
heating a substrate to a temperature less than 90° C. to provide a heated substrate;
depositing the deposition material substantially continuously on the heated substrate without an intermediate isolation step using a microchannel applicator;
allowing the deposition material to form a device-quality film on the substrate without heating to a temperature required for annealing, where the film is an epitaxial nanostructured film, a nanocrystalline film, an epitaxial film comprising embedded nanocrystals, a superlattice film, a composition gradient film, a composite film comprising core-shell nanoparticles, or combinations thereof; and
forming an electronic device comprising the substrate and the film, where the device is a transistor, a solar cell, a light emitting diode, a detector, a sensor, or a switch.
20. The process according to claim 19 where the device is flexible.
21. The process according to claim 19 where the mixer is a micromixer.