Growth of GaN Single Crystals Using Ca−Li₃N Composite Flux

Abstract

A Ca−Li3N composite flux was introduced to grow GaN single crystals from Ga melts. The obtained GaN crystals were colorless and up to 4 mm at 800 °C under N2 pressure of about 2 atm. The effects of introducing the composite flux on the size distribution, morphologies, and yield of the GaN crystals were studied. It was found that the addition of Ca retarded the homogeneous nucleations to some extent and resulted in a more uniform size distribution of the GaN crystals in comparison with that grown using Li3N as flux only. The layered morphological feature on the GaN surface suggested that the layer growth mechanism was probably enhanced by the composite flux. The yield of the crystals was strongly dependent on the flux compositions. These results provided a possible new route for improving the growth of GaN crystals from melts in the future by optimizing the composite flux.

Synthesis of Scandium Nitride Crystals from Indium–Scandium Melts

“…This fact suggests that Sc itself favors the dissolution of nitrogen into the In‐Sc melt. This assumption is supported by the reported improvement of nitrogen dissolution in GaN and AlN fluxes after the incorporation of additives . In general, the additives having a strong biding energy with nitrogen could diminish the nitrogen activity in the metal solution, thus promoting the nitrogen solubility .…”

“…The flux growth method is another typical technique for the growth of compounds that sublimate before melting, which has not been investigated yet for the case of ScN. This method enables the growth of high‐quality nitride crystals at comparatively low temperatures . More importantly, it is possible to deposit large‐area thin films or to produce bulk crystals by applying a substrate or a seed‐mediated growth, respectively .…”

Exploration of Ba3N2 flux for GaN single-crystal growth

“…6. One reason may be from the high viscosity of Ga-Ba melt in terms of our former work [15,17,18]. High viscosity that will retard the nitrogen diffusion in the growth system and lead to the local fluctuation of nitrogen concentration.…”

“…The Sodium flux method [12][13][14], developed by Yamane et al, was applied to grow GaN single crystals of mm scales at 600-800 1C under a nitrogen pressure of 5-100 atm. The Li 3 N flux method under more moderate conditions was explored to synthesize GaN crystals up to 4 mm at about 800 1C under a nitrogen pressure of 1-2 atm [15][16][17]. These presented investigations suggest that the flux method is perhaps promising for low-cost and large-scale growth of GaN crystals.…”

Thermodynamic modeling of the Ga–N–Na system

“…Up to now, several techniques [4][5][6][7][8][9][10][11][12] have been developed to grow large-sized and high-quality single crystals of practical applications. Among these methods, the flux method is distinct in its relatively moderate growth conditions.…”