Impact of growth conditions on AlN/GaN heterostructures with in-situ SiN capping layer

Abstract : In this work we have studied the growth of AlN barriers on GaN channels by Metal-Organic Vapor Phase Epitaxy (MOVPE). We have shown that an SiN in-situ capping layer is critical on AlN barrier layers. In addition, we have shown that an extreme reduction of NH3 partial pressure results in gallium incorporation into the layers around 22%. However, we have shown that lesser reductions of NH3 partial pressure allow us to achieve thin (3 nm) AlN layers capped with SiN which have a high quality crack free surface and state of the art Rsheet values < 330 Ohm/sq for such thin layers.