Growth of Large GaN Single Crystals on High-Quality GaN Seed by Carbon-Added Na Flux Method

Abstract

Seeded growth on high-quality GaN seed was studied using a carbon-added Na flux method. A GaN single crystal (8.6 mm long, 5 mm high) was grown in 96 h without polycrystal formation on a crucible. Under a carbon-added condition, dependence of the growth rate of the seed and the growth habit on the flux composition was studied. We found that the growth rate was higher with Ga-poor flux, resulting in a high growth rate of 30 µm/h along the c-axis and 33 µm/h along the a-axis (66 µm/h for both sides). The growth habit changed from prismatic to pyramidal with increasing Ga composition.

Vapor-phase epitaxial growth of GaN films using Ga2O vapor and NH3

“…a high growth rate, could be grown at high growth temperatures. The increase in the growth rate of the smooth (0001) GaN (Type I) layers at a high growth temperature is thought to be caused by the difference in the surface energy for (0001) and (10)(11) since the surface stability strongly depends on the growth temperature [16]. The relationship between P Ga 2 O and the growth morphology is consistent with the results presented by the authors [13].…”

“…The decrease in the oxygen incorporation is likely caused by the decrease in the density of pits composed of (10-11) facets. Cruz et al reported that the oxygen incorporation is strongly affected by the crystal orientation, with higher oxygen concentration observed in (10)(11) in comparison to (0001) GaN [17]. Second, the increased volatility of Ga 2 O 3 reduces the oxygen incorporation into GaN.…”

“…True GaN substrates with a low defect density are desired. The growth of GaN bulk single crystals has been attempted using various methods, such as hydride vapor phase epitaxy (HVPE) [2][3][4], high-pressure solution growth (HPSG) [5], ammonothermal growth [6][7][8], and Na-flux growth [9][10][11]. HVPE has the advantage of a high growth rate of over 100 mm/h [3,4], and GaN substrates produced by this method are now commercially available.…”

Growth of bulk GaN crystals by Na flux method

“…In this section, we report seeded growth on highquality GaN seeds with a high growth rate without the formation of polycrystals on the crucible by the addition of carbon in the Ga-Na melt [28]. We also describe the flux composition dependence of the growth rate and growth habit of the seed.…”

“…Some approaches such as hydride vapor phase epitaxy (HVPE) [1][2][3], ammonothermal growth [4][5][6], high pressure solution growth [7][8][9], and Na flux methods [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] have been developed to realize the bulk GaN crystals. HVPE method is the most common technique accepted in the industry because of the high growth rates (>200~300 μm/h).…”