Electrical Conduction of AlGaN/GaN 2DEG Heterostructures Grown on Si(111)

Abstract

PACS : 73.20.At; 73.40.Kp; 81.15.Hi The growth of III-nitrides on Si(111) substrate by plasma assisted molecular beam epitaxy is addressed. Growth optimization of GaN layer is reported. Different III-N flux ratio, substrate temperature and buffer layer structures were chosen as optimization parameters. Significant improvement of the GaN properties is achieved using AlGaN/AlN buffers. Temperature-dependent Hall effect experiments show a complex behavior, whereby p-and n-type conductivity is observed.Introduction Silicon is an attractive substrate for GaN-based devices because of its physical properties, crystal quality, doping capability, thermal stability, low cost and well known Si technology. The crystal perfection is better than any other substrate material used for GaN epitaxy and its surface could be prepared with extremely smooth finishes. To date, the quality of GaN epitaxial layers on silicon has been much poorer than that on sapphire or silicon carbide, due to large lattice and thermal expansion coefficient mismatch, and the tendency of silicon to form an amorphous silicon nitride layer when exposed to reactive nitrogen sources. Nevertheless, GaN devices have been already demonstrated on Si substrates including LEDs and HEMTs [1]. In this work we first concentrate on the III-nitride MBE growth on Si(111) substrates and finally on the Hall effect characterization of 2DEG AlGaN/GaN heterostructures.

Mn incorporation in GaN thin layers grown by molecular-beam epitaxy

“…All samples were grown on p-doped Si(111) substrates with a specific resistance of 7-21 cm. To avoid the formation of Si x N y at the substrate interface the nucleation of the growth is performed as described in [16]. An AlN buffer layer is grown at 770 • C, with a typical thickness of about 80 nm.…”