The HNPS growth method is a temperature gradient method based on a direct reaction between liquid gallium (Ga) and gaseous nitrogen (N2) at high temperature (up to 1800 K) and high nitrogen pressure (up to 1 GPa).

Nitrogen molecules dissociate on the gallium surface and dissolve in the metal. Therefore, the crystals are grown from the solution of atomic nitrogen (N) in liquid gallium. The gallium nitride crystals can be grown spontaneously from the walls of the crucible, usually forming hexagonal platelets or needles. They are distributed randomly in the supersaturated zone of the solution.

For a seeded crystallization, GaN or foreign seeds have to be immersed in the gallium in the supersaturated zone of the solution. Recently, the multi-feed-seed (MFS) configuration in the HNPS growth method has been proposed and developed. This configuration was based on the conversion of free-standing HVPE-GaN crystals to free-standing, pressure grown HNPS-GaN of a much higher quality than the seeds. The great strength of this approach is that it yields several GaN crystals from one run - what’s more, the crystals satisfy all the criteria for being substrates. A few following presentations about HNPS growth of GaN allow to explain better this technology.

High Nitrogen Pressure Solution (HNPS) growth method

More articles in this field:

A.E.F. de Jong, V. Vonk, M. Boćkowski, I. Grzegory, V. Honkimäki, E. Vlieg "Complex Geometric Structure of a Simple Solid-Liquid Interface: GaN(0001)-Ga" Phys. Rev. Lett. (feb 2020)
B. Sadovyi, P. Sadovyi, I. Petrusha, I. Dziecielewski, S. Porowski, V. Turkevich, A. Nikolenko, B. Tsykaniuk, V. Strelchuk, I. Grzegory "Physical properties of Ga-Fe-N system relevant for crystallization of GaN Initial studies" Journal of Crystal Growth (feb 2019)
S. Porowski, B. Sadovyi, I. Karbovnyk, S. Gierlotka, S.J. Rzoska, I. Petrusha, D. Stratiichuk, V. Turkevich, I. Grzegory "Melting of tetrahedrally bonded semiconductors: anomaly of the phase diagram of GaN?" Journal of Crystal Growth (jan 2019)
Petro Sadovyi, Bogdan Sadovyi, Michal Bockowski, Igor Dziecielewski, Sylwester Porowski, Izabella Grzegory "First Step in Exploration of Fe-Ga-N System for Efficient Crystallization of GaN at High N2 Pressure" Phys. Status Solidi A (apr 2018)
Dirk Ehrentraut, Michal Bockowski "High-Pressure, High-Temperature Solution Growth and Ammonothermal Synthesis of Gallium Nitride Crystals" Handbook of Crystal Growth ( 2015)
Michal Bockowski "High nitrogen pressure solution growth of GaN" Jpn. J. Appl. Phys. (sep 2014)
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Michal Boćkowski, Pawel Strąk, Izabella Grzegory, Sylwester Porowski "High Pressure Solution Growth of Gallium Nitride" Technology of Gallium Nitride Crystal Growth ( 2010)
I. Grzegory, M. Boćkowski, S. Porowski "GaN Bulk Substrates Grown under Pressure from Solution in Gallium" Bulk Crystal Growth of Electronic, Optical & Optoelectronic Materials (jul 2010)