SECONDARY-ION MASS-SPECTROSCOPY STUDY OF ZN OR CD IMPLANTED AND RAPIDTHERMALLY ANNEALED PD GE CONTACTS TO P-IN0.53GA0.47AS/

Backside secondary ion mass spectroscopy is used to examine elemental redistribution in Zn or Cd implanted Pd/Ge contacts to p-InGaAs. A qua ternary Pd-In-Ga-As layer is observed at annealing temperatures of 200 -250-degrees-C. At temperatures >250-degrees-C, this layer disappears due to PdGe formation and InGaAs regrowth. Excess Ge diffuses to the c ontact interface. Cd and Zn accumulate inside the regrown InGaAs creat ing a thin, highly doped layer. Due to its abrupt interface and the fo rmation of a highly doped layer beneath the contact, this implanted Pd /Ge contact scheme is a promising candidate for shallow ohmic contacts to p-InGaAs.