GaN on Si device substrate with GaN layer including sub-10nm SiNx interlayers that promote crystal growth with reduced threading dislocations

摘要

A gallium nitride (GaN) semiconductor substrate for grown of nitride semiconductor devices comprises an underlying wafer that carries a first GaN layer that has one or more very thin silicon nitride SiNx inter-layers therein. These Si N x inter-layer(s) are 0.5nm to 10nm thick and the GaN penetrates through one or more portions of the inter-layer preferably to form discrete crystalline structures (3D GaN). Preferably these crystalline structures help reduce threading dislocations when the GaN layer is grown, by MOVPE for example. Additionally, below the GaN layer, an aluminium nitride AlN nucleation layer may lie on the underlying wafer with an aluminium gallium nitride AlGaN buffer layer above the AlN and below the GaN layer. The underlying wafer may be silicon Si. The AlGaN layer may have a graded alloy content so the amount of aluminium decreases from the Si wafer towards the GaN layer. The GaN layer may be undoped and a second, doped, GaN layer may be formed on top, the dopant concentration of Si or Ge increasing with increasing distance from the first undoped GaN layer. Devices may be formed including MQW structures which may comprise LED or Solar (photovoltaic) devices. The substrate may be from 6 inches (15cm) to 12 inches (30cm) in diameter.