A pathway to compound semiconductor additive manufacturing

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Research Letter

A pathway to compound semiconductor additive manufacturing Jarod C. Gagnon, Michael Presley, Nam Q. Le , Timothy J. Montalbano, and Steven Storck, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA Address all correspondence to Jarod C. Gagnon at [email protected] (Received 28 June 2019; accepted 14 August 2019)

Abstract The rise of additive manufacturing (AM) has enabled the rapid production of complex part geometries across multiple material domains. To date, however, AM of inorganic semiconductor materials has not been fully realized due to the difficulty of forming single-crystal materials with traditional AM processes. Here, we demonstrate a novel semiconductor synthesis method using a combination of liquid and gas precursors to additively print gallium nitride. Growth rates of 1–2 µm/min are demonstrated in printed regions while maintaining epitaxial alignment with the substrate. We also outline critical variables for the future development, improvement, and implementation of the proposed process.

Introduction With the advent of additive manufacturing (AM), many materials and applications have benefited from the ability to 3D print complex structures.[1] Layer-by-layer printing processes allow rapid production of complex geometries enabling significant capability improvements across multiple domains. Examples include low-cost rapid prototyping, part count reduction in jet engines, increased complexity in sand casting molds, and light-weighting of ceramic components.[2,3] To date, however, the research of additively manufactured semiconductors has been minimal. The ability to print complex geometry, single-crystal semiconductor materials will revolutionize the way high power electronics are fabricated. Current semiconductor device architectures are limited to what is achievable using standard semiconductor device fabrication methods, which are usually a combination of thin-film deposition, etching, regrowth, and other processing steps to develop a final device.[4,5] Process and material limitations on material quality, process speed, dimensional accuracy, and achievable geometries restrict the development of new device architectures. Being able to additively build semiconductor structures could reduce the cost associated with more complex device structures that can only be formed through multiple etch and growth steps using current processes. This benefit is of particular interest for wide bandgap semiconductor materials such as gallium nitride (GaN). GaN is a material widely used in optoelectronic, high-power, and high-frequency device applications due to its wide (3.4 eV) direct bandgap.[6] Furthermore, ternary compounds such as AlGaN can be formed with even wider bandgaps tailored to specific applications, making GaN an important base material for high-power devices. As current device limitations are being reached,

there is an interest in developing more complex vertical device architectures and lower dislocation density material to further