Fabrication of GaN crystals with low threading dislocation density and low resistivity by thin flux growth in the Na-flux point seed technique

摘要

We investigated the electrical properties of low threading dislocation density (TDD) GaN crystals grown by the thin flux growth method in the Na-flux point seed technique for the first time. In addition, we attempted to fabricate GaN crystals with further lower TDD and curvature by using point seeds having a smaller diameter of 250 mu m, compared to that from a previous study having a diameter of 1000 mu m. As a result, the free carrier concentration was 1.1 x 10(20) cm(-3) with a resistivity of 9 x 10(-4) Omega cm. Moreover, TDD in about 80% of the observation area was on the order of 10(3) cm(-2) or less, and the radius of curvature of the GaN crystal was over 100 m for both a// and m//, due to the smaller-sized point seeds. These results suggest that low-TDD GaN crystals with low resistivity can be realized with this method, and Na-flux GaN crystals exhibit great performance as substrates of power devices. (c) 2020 The Japan Society of Applied Physics