Publication date: 1 February 2018
Source:Journal of Crystal Growth, Volume 483
Author(s): Daichi Dojima, Koji Ashida, Tadaaki Kaneko
For the growth of AlN single crystal with large diameter and low dislocation density on SiC substrate by physical vapor transport (PVT), a dislocation blocking buffer layer (DBBL) has been simply developed by optimizing the AlN growth parameters such as temperature gradient (ΔT), substrate temperature (Tsub ), and N2 partial pressure (PN2 ) at the initial growth stage. Increase in ΔT resulted in the formation of an abrupt AlN/SiC interface due to the suppression of inhomogeneous thermal decomposition at the interface and the subsequent AlN unstable island growth. The well-defined AlN/SiC interface played an important role in controlling the two kinds of different AlN growth mode in-situ as functions of Tsub and PN2 . One is a continuous step-flow growth mode, and the other is a discontinuous platelet-like growth. The discontinuous AlN layer, consisting of thin AlN platelets and air-gaps inserted between the two adjacent platelets, acted as the DBBL. By introducing the DBBL at the initial growth stage, followed by the step-flow growth, continuous AlN layer with dislocation density of 1.7 × 106 cm−2 was achieved at a total growth thickness of 60 μm, which is two orders of magnitude lower than the previously reported value.
Source:Journal of Crystal Growth, Volume 483
Author(s): Daichi Dojima, Koji Ashida, Tadaaki Kaneko