Nitrides form a fascinating class of functional materials, though are still largely unexplored due to stringent synthesis constraints. For example, of the 447 computationally predicted thermodynamically stable ternary nitrides less than half have been synthesized. Even for the simpler binary nitrides, single crystal synthesis is demanding and constraint by the relative ease of their decomposition at elevated temperature.

Group-III nitrides, including In_1-xGa_xN, Al_1-xGa_xN, and cubic/hexagonal BN, are of scientific and technological interest in part due to their advantageous intrinsic materials properties: (ultra-) wide band gap, radiation hardness, extreme thermal conductivity, and mechanical hardness. Important applications include optoelectronic (IR through UV) and power electronic (e.g. high-power, high-frequency) devices. Critical to high-performance, high-efficiency device operation is the availability of large-area, high-quality single crystal substrates or boules, though these are expense and small at best and non-existent at worst. Improved nitride synthesis approaches are needed to improve upon existing materials and enable new devices. Furthermore, to access new material compositions/phases and improve upon crystal quality for device applications, enhanced thin film synthesis approaches are needed.

This talk will discuss important advances made in the realm of single crystal nitride synthesis using the ammonothermal method enabling high growth rate, high transparency GaN boules, while simultaneously laying the groundwork to explore the bulk, single crystal growth of cubic BN, hexagonal BN and InN for the first time. Advances in the complementary development of a novel, thin film synthesis platform consisting of a high pressure spatial chemical vapor deposition tool (HPS-CVD) capable of operating up to 100 atm will be discussed using computational fluid dynamic modeling.

Bio: Siddha Pimputkar (PhD 2012 - UCSB under Nobel Laureate Shuji Nakamura) is an Assistant Professor in the Department of Materials Science & Engineering at Lehigh University. He has published 3 book chapters, 21 papers (with ~3300 citations overall), holds 3 patents (with 15 additional filed patent applications), and given 22 invited talks. He has received 4 NSF grants including the NSF CAREER award. His chief expertise lies in the bulk single crystal growth and epitaxial thin film growth of next-generation, ultra-wide band gap semiconductors (e.g. group-III nitrides and cubic/hexagonal BN as (opto-)electronic materials for power/RF electronics and optical emitters) along with the development of advanced equipment, such as high-pressure autoclaves with in-situ monitoring capabilities and a novel high-pressure, spatial metal-organic chemical vapor deposition tool (HPS-CVD) needed to synthesize novel nitrides. Dr. Pimputkar’s primary focus is on studying relationships between crystal growth conditions, growth mechanisms and material defects, while vertically integrating to demonstrate rudimentary devices demonstrating the extraordinary potential of these materials. He has been awarded the Young Scientist Award from AACG along with the Lehigh Early Career Award for Distinguished Teaching in 2021. More info at: www.pimputkar.org