Dr. Pimputkar’s research is currently focused on synthesizing bulk and thin film single crystal, nitrogen-containing materials. Materials of interest include the ammonothermal growth of ultrawide bandgap semiconductor cubic BN (for future use in power electronic devices and systems that require super hard materials), the ammonothermal growth of bulk InN (as substrates for efficient long wavelength emitters based on high-indium content devices), and the flux growth of bulk, ternary III-N such as AlGaN and InGaN (for use as substrates for high efficiency, low defect density UV and visible-light optoelectronic devices). An ammonothermal-hydrothermal hybrid approach is being investigated for growth of single crystal oxy-nitrides (a first of its kind). To enable growth of decomposition limited materials, a new thin film growth equipment is being developed. This novel high-pressure CVD tool will enable thin-film, single crystal growth of high-indium content Group III-N semiconductors providing growth of InGaN and AlInN across the entire solid solution spectrum at temperatures in excess of 1100 °C.
Background
Semiconductor materials are useful in many electric device applications for their exceptional material properties. Nitrides are a fascinating class of functional materials that remain largely unexplored due to demanding synthesis constraints. Of the 447 predicted stable ternary nitrides, less than half have been synthesized. Many computationally predicted stable nitrides with intriguing properties have been proposed. Their single‑crystal synthesis from solution is challenged due to limited synthesis process parameter windows and insufficient solubility of nitrogen or cations at temperatures below their decomposition temperature.
Technology Overview
This technology is a new method for synthesizing nitrogen-containing semiconductor materials, particularly focusing on the controlled decomposition of lithiated nitrogen-containing precursors in a liquid flux. By utilizing a lithium nitride-based solvent under controlled conditions, it overcomes traditional limitations associated with nitrogen solubility and supply in the melt, thereby enabling the synthesis of high-purity single-crystal nitrides. These materials include, but are not limited to, gallium nitride (GaN), boron nitride (BN), and aluminum nitride (AlN), which are pivotal in various semiconductor applications.
Liquification and controlled decomposition of the precursor results in the deposition of a crystalline nitride and is achieved via controlling the lithium vapor pressure, nitrogen overpressure and temperature gradients, while alloy composition is achieved via control of the melt composition. The newly developed synthesis equipment is suitable to operate up to at least 100 atm and 1000 °C. In situ data is fed through a machine learning algorithm to continuously and automatically control synthesis conditions to yield targeted material compositions. This approach does not rely on dissolution and diffusion of nitrogen through the flux from the gas phase leading to transformative opportunities in rapid, scalable synthesis of nitride single‑crystals.
Technologies
- Metallic Elements
- Nitrogen
Benefits
- Enables the synthesis of a wider range of ternary and higher-order nitride semiconductor materials.
- Overcomes limitations related to nitrogen solubility and transport in conventional methods.
- Facilitates controlled composition and polymorph tuning for desired properties of synthesized nitride materials.
- Provides a scalable approach to the synthesis of large, high-purity high-quality single‑crystal nitrides.
- Increases the commercial viability of synthesizing ternary alloys in formats larger than thin film or powder form.
- Improves the scalability of semiconductor material production under industrially accessible conditions.
Applications
- Next-generation power electronics devices with superior performance and efficiency.
- Energy-efficient lighting and high-power UV emitters.
- Manufacturing of super-hard materials for industrial applications.