Sequential Infiltration Synthesis of Group 13 Oxides in Polymers
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Solution Overview
Problem
Current sequential infiltration synthesis (SIS) methods are limited in their ability to form a diverse range of group 13 oxides within polymers, particularly electrically conductive materials, due to challenges in precursor diffusion, reactivity, and kinetics, which restricts the expansion of the materials library and functional properties.
Innovation Solution
A method for depositing group 13 oxides, such as indium or gallium oxides, using a SIS process involving pulsing metal precursors and co-reactants within a reactor, with controlled exposure times and partial pressures, to achieve infiltration and binding within the polymer base material, allowing for the growth of thick, conductive films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional ALD processes are used to form metal oxides on polymer surfaces, then layer formation is achieved, but the materials are limited to surface coatings rather than bulk integration and the material library is restricted
Solution Approach 1:
The synthesis process is divided into sequential steps: precursor diffusion into polymer, precursor reaction with polymer functional groups, and oxide formation. This segmentation enables control over material formation at the molecular level while maintaining process manageability
Solution Approach 2:
Polymer functional groups act as intermediaries that facilitate precursor diffusion and reaction. The polymer template serves as a mediator that enables selective infiltration and binding of metal precursors, expanding the material library without requiring complex process modifications
2Quantity of substance
If precursor diffusion into polymer is enabled for SIS, then bulk material formation is achieved, but reactivity issues and kinetic challenges arise
Solution Approach 1:
The process utilizes controllable parameters including precursor pulse time, exposure time, partial pressure, and temperature to optimize diffusion and reaction kinetics. By adjusting these parameters, thick oxide films can be formed reliably while managing reactivity challenges
Solution Approach 2:
The SIS process employs periodic pulsing of precursors followed by exposure and purge cycles. This periodic action enables controlled diffusion and reaction, ensuring reliable oxide formation while managing the reactivity and kinetic challenges of precursor-polymer interactions
3Length of stationary object
If extended precursor exposure is used to increase oxide thickness, then thicker films are formed, but diffusion kinetics and reactivity control become more difficult
Solution Approach 1:
The process uses periodic pulsing of precursors with controlled exposure times between pulses. This allows thick oxide films to be formed through multiple cycles while maintaining control over diffusion kinetics and reactivity, avoiding excessive total exposure time
Solution Approach 2:
The SIS process maintains continuous useful action through overlapping diffusion and reaction steps. Precursor diffusion into the polymer occurs concurrently with reaction at functional groups, enabling efficient thick film formation without proportionally increasing total process time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the growth of indium oxide films exceeding 150 nm thickness with linear growth rates and achieves ample electrical conductivity, expanding the SIS library and demonstrating the viability of SIS for transparent conductive metal oxides.
Implementation Method 1
the exposure times are much longer to enable diffusion into the polymer free volume
Implementation Method 2
vapor residence is often further promoted by adduction to polymer functional groups
Implementation Method 3
the co-reactant precursor infiltrating at least a portion of the base material and reacting with the first metal adduct within the base material to form the oxide
Data Source
AI summary
The sequential infiltration synthesis (SIS) of group 13 indium and gallium oxides (In2O3 and Ga2O3) into polymethyl methacrylate (PMMA) thin films is demonstrated. Examples highlight the an SIS process using trimethylindium (TMIn) and trimethylgallium (TMGa), respectively, with water. In situ Fourier transform infrared (FTIR) spectroscopy reveals that these metal alkyl precursors reversibly associate with the carbonyl groups of PMMA in analogy to trimethylaluminum (TMAl), however with significantly lower affinity. SIS with TMIn and water enables the growth of In2O3 at 80° C., well below the onset temperature of atomic layer deposition (ALD) using these precursors.