X-Ray Absorption Fine Structure Spectroscopic Investigation at Ge K-Edge of AuGe/Ni/AuGe Ohmic Contact to GaAs/AlGaAs

X-ray absorption fine structure spectroscopy (XAFS) has been employed to investigate the crystallographic structural changes that develop at the AuGe-based metal interface to the GaAs/AlGaAs heterostructures. A stack of AuGe/Ni/AuGe is sequentially deposited over the GaAs/AlGaAs substrate by thermal and electron beam evaporation techniques without breaking the vacuum in between the deposition. These stacks were annealed at 100°C and 300°C in a nitrogen-rich atmosphere. XAFS measurements were carried out at Ge K-edge to investigate the crystallographic structural changes developed at the interface as a function of annealing temperature. Further, the effect of Ni layer thickness on the different crystal structures developed at the interface is also reported.