Growth of GaN on ZrB2 substrate by metal-organic vapor phase epitaxy

Growth of GaN by metal-organic vapor phase epitaxy (MOVPE) on metallic zirconium diboride (ZrB2) substrate was investigated. Cross-sectional transmission electron microscopy (TEM) showed that cubic ZrBxN1−x is formed on the surface when ZrB2 is exposed to ammonia-containing atmosphere, which protects the nucleation of GaN or AlN. We solved the problem by covering ZrB2 surface with very thin AlN or GaN at low temperature, thereby achieving high-quality GaN growth with a dislocation density less than 108 cm−2. Direct conduction was achieved through the back of ZrB2 and the surface of Si-doped GaN.